ACS Publications. Most Trusted. Most Cited. Most Read
Quick View

OR SEARCH CITATIONS

My Activity
Publications
CONTENT TYPES

Figure 1Loading Img
Download Hi-Res ImageDownload to MS-PowerPointCite This:J. Nat. Prod. 2019, 82, 1, 35-44
RETURN TO ISSUEPREVArticleNEXT

Antibacterial Aromatic Polyketides Incorporating the Unusual Amino Acid Enduracididine

  • Paolo Monciardini*
    Paolo Monciardini
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    *E-mail: [email protected]. Phone: +39 02 56660231.
    More by Paolo Monciardini
    Orcidhttp://orcid.org/0000-0002-8727-2791
  • , 
  • Alice Bernasconi
    Alice Bernasconi
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Alice Bernasconi
  • , 
  • Marianna Iorio
    Marianna Iorio
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Marianna Iorio
    Orcidhttp://orcid.org/0000-0001-8669-5875
  • , 
  • Cristina Brunati
    Cristina Brunati
    KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Cristina Brunati
  • , 
  • Margherita Sosio
    Margherita Sosio
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Margherita Sosio
  • , 
  • Laura Campochiaro
    Laura Campochiaro
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Laura Campochiaro
  • , 
  • Paolo Landini
    Paolo Landini
    Bioscience Department, Università degli Studi di Milano, Via Celoria 2, 20122 Milano, Italy
    More by Paolo Landini
  • , 
  • Sonia I. Maffioli
    Sonia I. Maffioli
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Sonia I. Maffioli
  • , and 
  • Stefano Donadio
    Stefano Donadio
    NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    More by Stefano Donadio
Cite this: J. Nat. Prod. 2019, 82, 1, 35–44
Publication Date (Web):January 7, 2019
https://doi.org/10.1021/acs.jnatprod.8b00354

Copyright © 2019 American Chemical Society and American Society of Pharmacognosy. This publication is licensed under these Terms of Use.

Request reuse permissions
  • Open Access

Article Views

3528

Altmetric

-

Citations

7
LEARN ABOUT THESE METRICS
PDF (2 MB)
Get e-Alerts
Supporting Info (1)»
SUBJECTS:

Abstract

High Resolution Image
Download MS PowerPoint Slide

The increasing incidence of infections caused by drug-resistant pathogens requires new efforts for the discovery of novel antibiotics. By screening microbial extracts in an assay aimed at identifying compounds interfering with cell wall biosynthesis, based on differential activity against a Staphylococcus aureus strain and its isogenic l-form, the potent enduracyclinones (1, 2), containing the uncommon amino acid enduracididine linked to a six-ring aromatic skeleton, were discovered from different Nonomuraea strains. The structures of 1 and 2 were established through a combination of derivatizations, oxidative cleavages, and NMR analyses of natural and 13C–15N-labeled compounds. Analysis of the biosynthetic cluster provides the combination of genes for the synthesis of enduracididine and type II polyketide synthases. Enduracyclinones are active against Gram-positive pathogens (especially Staphylococcus spp.), including multi-drug-resistant strains, with minimal inhibitory concentrations in the range of 0.0005 to 4 μg mL–1 and with limited toxicity toward eukaryotic cells. The combined results from assays and macromolecular syntheses suggest a possible dual mechanism of action in which both peptidoglycan and DNA syntheses are inhibited by these molecules.

Our ability in controlling infections, which has been taken for granted for decades after the introduction in clinical practice of antibiotics, is currently at risk due to the continuous rise of infections sustained by antibiotic-resistant microorganisms. Multi-drug-resistant pathogens are now routinely isolated, severely impairing our ability to manage bacterial infections. (1,2) To address this threat to human (and animal) health requires increased efforts toward discovery and development of novel anti-infective substances, not affected by prevailing resistance mechanisms. (1,2) Ideally, novel antimicrobials should belong to new chemical classes to minimize cross-resistance with marketed antibiotics. (3) Natural products represent a major source of approved antibacterials: (4,5) the majority of antibiotics in clinical use are microbial metabolites or their derivatives, typically from actinomycetes. (2,4) Despite extensive screening during the “golden era” of antibiotic discovery, molecules with novel structures and modes of action can still be found among microbial metabolites. Recent examples include teixobactin (6) and pseudouridimycin, (7) which, although acting on well-established bacterial targets (cell wall and RNA biosynthesis, respectively), do so with mechanisms differing from those of other molecules targeting the same pathways and thus are active against resistant pathogens.
In our search for novel classes of antibacterial molecules, we have previously described an approach based on mining our proprietary database, which contains results of several antibacterial high-throughput-screening (HTS) assays performed on more than 100 000 microbial extracts. (8) While HTS applies rigid filters for identifying a workable number of candidates for further analyses, a posteriori evaluation of the HTS data permits selection of candidates that were not previously pursued. By re-evaluating data from an HTS phenotypic screen aimed at identifying molecules inhibiting bacterial cell wall biosynthesis, (9) we have reported different lanthipeptides, (10,11) including compounds with unusual structural features and unexpected bioactivities. (10−12)
Here we further expand on this data mining approach and report on the isolation of aromatic polyketides containing the uncommon amino acid enduracididine installed on a fused six-ring skeleton. These molecules, dubbed enduracyclinones, are highly active against Gram-positive pathogens, including antibiotic-resistant strains.

Results and Discussion

ARTICLE SECTIONS
Jump To

Data Mining

The HTS database contains data on a phenotypic assay aimed at identifying likely inhibitors of bacterial cell wall biosynthesis. About 120 000 microbial fermentation extracts were analyzed by an assay based on differential activity against a Staphylococcus aureus strain and its isogenic l-form, i.e., a variant empirically adapted to grow in the absence of a cell wall in an osmotic-protective medium. (9) Extracts inhibiting growth of S. aureus at a concentration at least 8 times lower than that required for growth inhibition of the l-form were assumed to interfere with cell wall biosynthesis. Positive samples were further assayed for maintenance of activity after incubating the extracts with beta-lactamases or with d-Ala-d-Ala (these tests were meant to discard β-lactamase-sensitive compounds and d-Ala-d-Ala binders, respectively) before further characterization. By searching the HTS database, however, we identified 17 extracts that, albeit fulfilling the selection criteria (lack of or reduced activity against l-forms), had not been further analyzed during the original screening. The corresponding strains were therefore processed, and the extracts obtained from 12 cultures confirmed activity against S. aureus. Ten of these extracts retained activity against one multi-drug-resistant (MDR) S. aureus strain and were further processed (Supplementary Table S1). One extract was found to contain the lantibiotic NAI-802, (10) a variant of actagardine likely to target cell wall biosynthesis, and another extract was found to contain the thiopeptide nosiheptide, a molecule whose primary target is translation but which, for unknown reasons, is known to be less active against l-forms. (13) The other eight strains produced the same compound, as described below.

Discovery of Enduracyclinones from Nonomuraea spp

Extracts from the eight strains contained the same active fractions correlating to peaks with retention times of 9.5 (major peak), 10, and 12 min (peaks A, A′, and B, respectively, as shown in Figure 1). The peaks showed m/z [M + H]+ of 711, 697, and 713, respectively, and similar UV–vis spectra (absorption maxima were at 244, 283, 334, and 445 nm for peak A). The molecules appeared to be very stable in MS fragmentation conditions, with the ready loss of only a 44 amu fragment.

Figure 1

Figure 1. HPLC trace of an ethanol extract from strain ID40491 (see text for details).

High Resolution Image
Download MS PowerPoint Slide
The corresponding eight actinomycete strains were analyzed by comparing their nearly complete 16S rRNA gene sequences and assigned to three distinct lineages within the genus Nonomuraea (Supplementary Table S1). One of the lineages is represented by six strains isolated from four soil samples collected in different locations in Italy or from plant specimens from Scotland and Italy. These strains showed 99.7–100% identity in the 16S rRNA gene sequences among themselves and to Nonomuraea endophytica. The two additional lineages are represented by a single strain each, originating from Kenyan and Honduras soils and showing relatively low 16S identity with described species (98.4% with Nonomuraea candida or 98.9% with Nonomuraea salmonea). Comparable levels of the peaks correlated to biological activity were observed for the six European strains, and strain ID40491 was chosen for further analyses. Under the best conditions, strain ID40491 produced about 500 mg L–1 peak A. The remaining European strains produced at least 100 mg L–1 peak A.

Purification and Structure Elucidation

The active peaks were associated with both the mycelium and the cleared broth. Therefore, both mycelium and cleared broth were processed, and the active compounds were retrieved by exploiting their low aqueous solubility at pH 5 and their increased solubility at pH 9. Further purification afforded a sample containing HPLC peaks A and A′ in a 9:1 ratio and another containing A, B, and A′ in a 5:3:2 ratio. From the first sample a small amount of a highly pure A peak sample was generated (see Experimental Section for purification procedures). To help structure elucidation, the 13C–15N-labeled compounds were also prepared by growing strain ID40491 in a uniformly labeled medium (see Experimental Section) that afforded a purified sample of peaks A and A′ (in a 9:1 ratio) with a 95% 13C- and 15N-enrichment (Supplementary Figure S1). Unless otherwise stated, all chemical and bioactivity analyses were performed on samples containing peaks A and A′ in a 9:1 ratio.
The main congener 1 (peak A) has a molecular formula of C36H30N4O12 with 24 double-bond equivalents, as deduced by high resolution mass spectrometry (HRMS). In the presence of trimethylsilyldiazomethane, a 14 amu heavier product was formed, consistent with a methyl ester of 1, while N,N-dimethylpropylamine in the presence of condensing agents converted 1 into a m/z 795 [M + H]+ compound, consistent with the formation of the corresponding amide. The MS/MS data (loss of 44 amu, see above) and the results from these reactions suggested the presence of a free carboxylic acid. The structure of 1 (Figure 2) was established by a combination of one- and two-dimensional NMR analyses, performed on the natural and the 13C–15N-labeled compound, and confirmed by selective oxidative cleavage, as explained below.

Figure 2

Figure 2. Structures of compounds and NMR correlations. (a) Structures of 1 and 2. (b) Main 1H–1H COSY, NOESY, and 1H–15N HMBC correlations. (c) Observed HMBC and 13C–13C COSY correlations of 1.

High Resolution Image
Download MS PowerPoint Slide
1D and 2D NMR analyses established the presence of a polycyclic aromatic system linked to a nitrogen-rich aliphatic acid. The 1H NMR data (Table 1, Figure 2) of 1 displayed four aromatic protons at δH 9.58, 6.80, 7.14, and 6.64 ppm, the latter two showing a meta-coupling constant (J = 2.1 Hz); three methoxy (δH 3.98, overlapped), one N-methyl (δH 2.89) and one C-methyl (δH 2.59); two nitrogen-bound protons at δH 8.17 and 8.03 ppm; and two phenolic signals at δH 11.30 and 13.30 ppm. In addition, the major spin system corresponded to a four-carbon chain formed by an amino acid-alpha proton at δH 5.05 ppm (H-18) directly connected to a CH2 at 2.02–2.73 ppm (H-19a and b), followed by another CH at 4.09 ppm (H-20) and a further diasterotopic methylene at 3.30–3.84 ppm (H-24a and b). The analysis of proton and carbon chemical shifts (Table 1) together with correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), and nuclear Overhauser enhancement spectroscopy (NOESY) correlations suggested that C-20 and C-24 are trapped in a rigid structure. Furthermore, a guanidine unit was identified through the heteronuclear multiple bond correlation (HMBC) of the N-methyl group to an sp2 carbon at δC 158.2 ppm (C-22) and the NOESY signals of the proton at 8.02 ppm with the proton at 8.17 ppm and the N-methyl group. Moreover, the NOESY correlation of the N-methyl group with one of the methylene protons at C-24 (H-24b, at δH 3.84 ppm) and of the alpha proton at 5.05 ppm with the proton at 8.17 ppm and with the C-methyl at 2.59 ppm established that the rigid structure is a five-membered ring arising from an N-methyl enduracididine linked through the α-amino group to the aromatic system.
Table 1. NMR Spectroscopic Data (300 MHz, DMSO-d6) for Enduracyclinone A in DMSO-d6
position δC, type δH (J in Hz) δN, type
1     197.3, N
2 158.0, C    
2a 118.7, C    
3 182.3, C    
3a 129,8, C    
3b 131.2, C    
4 125.5, CH 9.58, s  
4 a 130.6, C    
5 181.4, C    
5a 134.8, C    
6 107.3, CH 7.14, d (2.1)  
7 164.8, C    
OH(7)   11.30, br s  
8 108.4, C 6.64, d (2.1)  
9 165.1, C    
OH(9)   13.30, s  
9 a 111.6, C    
10 185.6, C    
10a 122.1, C    
11 159.2, C    
OMe (11) 63.2, CH3 3.98 s  
11a 130.5, C    
12 155.6, C    
OMe (12) 62.6, CH3 3.98 s  
13 150.8, C    
OMe (13) 61.9, CH3 3.97 s  
13a 130.4, C    
14 181.9, C    
14a 143.6, C    
15 101.8, CH 6.80 s  
16 155.5, C    
17 22.3, CH3 2.59, s  
18 56.6, CH 5.05, m  
19 35.1, CH2 2.02, m–2.73, m  
20 50.9, CH 4.09, m  
21 NH   8.17, br s 90.4, NH
22 158.2, C    
22 NH   8.02 br s 71.3, NH
23     77.0, N
Me (23) 31.4, CH3 2.89, m  
24 55.2, CH2 3.38, m–3.84, m  
25 169.8, C    
Heteronuclear single quantum coherence (HSQC), HMBC, and monodimensional 13C experiments highlighted the presence of four quinonic carbonyls at δC 181.4, 181.9, 182.4, and 185.6 ppm, a carboxyl carbon at δC 169.8, and two other carbonyls at δC 158.0 and 158.2. A key signal was the aromatic CH-4, with a peculiar chemical shift at δH 9.58 ppm, correlating to a carbon at δC 125 ppm. It is known that aromatic hydrogens peri to quinones in natural anthraquinones are deshielded, with values ranging from 7.5 to 8.3 ppm. (14,15) In our case, H-4 appeared even more deshielded, suggesting the presence of a second quinone (E ring), linked angularly to the tetracyclinone (A–D rings). Moreover, this proton gave HMBC correlations with quinones C-5 and C-10, aromatic carbons C-10a and 11a, and the methoxy-substituted aromatic carbons C-11 and C-12, thus establishing the core A–E ring structure.
The relative position of the two quinone moieties was confirmed by treatment with 20% H2O2 at 60 °C (see Experimental Section for details). (16,17) Under these conditions both quinones were oxidatively cleaved, leading to the formation of a major species at m/z 637 [M + H]+, corresponding to the dicarboxylic product ox-1 following rupture of ring B (Figure 3), and of species at m/z 469 [M + H]+ (product ox-2) and m/z 279 [M + H]+ (product ox-3), after breaking ring E.

Figure 3

Figure 3. Oxidative cleavage of 1.

High Resolution Image
Download MS PowerPoint Slide
HMBCs of the two aromatic protons with meta-coupling constant (J = 2.1 Hz) enabled placing the substituents on ring A, with positions 7 and 9 bearing two phenols with different NMR behavior: while OH-7 gives a broad singlet with no significant 2D correlations, OH-9 presents a sharp signal at δH 13.30 ppm with HMBC correlations to C-8, C-9, and C-9a, suggesting that the phenol partakes in an intramolecular hydrogen bond with the quinone oxygen in peri position. The last ring, F, was established as a benzofused methyl-pyrimidone ring thanks to the HMBC correlations of proton H-15 at δH 6.80 ppm with quinone C-14, carbons C-2a and C-16, and methyl 17.
1H–15N-HMBC and 13C–13C COSY analyses of 13C–15N-labeled 1 allowed the assignment of all nitrogen chemical shifts and the identification of the cyclic amide, with N-1 correlating to CH3-17 and CH-15 (Table 1). Moreover, the majority of the carbon backbone connectivity of 1 was clearly established (Figure 2C).
As shown above (Figure 1), strain ID40491 produced also two minor congeners. Peak A′ showed a difference of 14 amu in comparison to 1, suggesting the lack of a methyl group (found m/z 697.1786 [M + H]+ for C35H28N4O12, calcd 697.1776). During oxidative cleavage, we also observed the formation of a minor m/z 455 [M + H]+ species along with product ox-2 (Figure 3), consistent with the lack of one of the three methoxy groups in rings C or D. However, the amount of des-methyl-1 was insufficient for further analyses, so the exact position of the free OH in this minor congener remains to be established.
HRMS indicated that peak B was associated with a C36H32N4O12 species (compound 2 in Figure 2) with 23 unsaturations (found m/z 713.2104 [M + H]+, 713.2095 calcd). The observation that, in the 1H NMR spectrum of 1:2:desmethyl-1 5:3:2, Me-17 integrated less than expected and that 2 easily converted into 1 under oxidative conditions (see Experimental Section) suggested that 2 differs from 1 for the lack of the unsaturation in the pyrimidone ring F (Figure 2).

Structural Features of Enduracyclinones

Overall, the metabolites produced by strain ID40491 consist of a highly oxygenated angular hexacyclic framework linked to an N-methylated enduracididine moiety. We therefore named the compounds enduracyclinones A (1) and B (2).
Similar polyketide skeletons are present in echinosporamicin (18) and related molecules (19) and in the polycyclic xanthone antibiotics, (20) but with differences in the saturation degree and decoration of the aromatic rings. Like echinosporamicins, enduracyclinones present a 1,4-benzoquinone moiety (ring B), instead of the gamma-pyrone found in the polycyclic xanthones, and a second quinone (ring E), an uncommon feature of xanthones. Indeed, xantholipin is the only representative of this class with a quinone in ring E, which is usually monooxygenated (as in cervinomycin and actinoplanone) or contains a para-biphenol (i.e., simaomycin and kibdelone). (20) The three adjacent oxygens present in rings C and D of enduracyclinones are found only in some polycyclic xanthones (lysolipin I and FD-594), (20) where ring D is nonaromatic, but not in echinosporamicins. Position C-4 is oxygenated in all xanthones (20) and echinosporamicins (19) but unmodified in 1 and 2, rendering the ABC ring system of enduracyclinones identical to bequinostatin’s, which however lacks the ring C methoxy and substantially differs in the remaining portion of the molecule. (21)
Most polycyclic xanthones and echinosporamicins present a cyclic amide (ring F), which can be substituted on the nitrogen with amine, methyl, or amino acid-derived heterocyclic structures. In particular, echinosporamicin carries a Gly-Ala-Ser tripeptide, (18) with the serine condensed on the alanine to form a piperazinone moiety, whereas an oxazolidine ring is fused to the pyrimidone in cervinomycin. (20) The unique feature of enduracyclinones is the presence of an N-methyl enduracididine moiety contributing to ring F. Enduracididine is an uncommon amino acid arising from arginine oxidization and cyclization and characterized by a guanidine embedded in a five-membered ring. Enduracididine has been so far encountered in a small number of natural products, where it can also be decorated with a β-hydroxy group. (22) In most cases (enduracidin, mannopeptimycin, and teixobactin), enduracididine incorporation proceeds through a nonribosomal peptide synthase (NRPS) assembly line, whereas in minosaminomycin the enduracididine moiety is linked to an amino sugar through an amide bond and carbamoylated at its α-nitrogen. Thus, enduracyclinones represent the first example of an enduracididine-containing aromatic polyketide and the first report of an N-methylated enduracididine moiety and represent another example of actinomycetes’ ability in performing combinatorial biosynthesis by joining different pathways for the generation of chemical diversity.
Enduracididine contains two stereogenic carbons that can occur in microbial metabolites in any R/S combination. (22) The stereochemistry of the enduracididine moiety in 1 could not be established experimentally. Indeed, the amide bond linking enduracididine to the polyketide core is trapped in a pseudo-aromatic ring, preventing easy release of this amino acid and direct comparison with suitable standards. The free rotation around the methylene in beta position (C-19) prevents using NMR data for relative stereochemistry assignment. As explained below, the enduracyclinone biosynthetic gene cluster (BGC) contains homologues of genes involved in l-enduracididine (i.e., 2S-4R-enduracididine) biosynthesis. (23,24) Since the d-enduracididine isomers occurring in enduracidin and mannopeptimycin are reported to be generated by NRPS-catalyzed epimerization at the α-carbon (23,25) and the enduracyclinone BGC does not apparently encode epimerases, it is reasonable to assume that the stereochemistry of the enduracididine moiety in 1 is S and R for the alpha (C18) and gamma (C20) carbons, respectively.

Putative Enduracyclinone Biosynthetic Gene Cluster

The structure of enduracyclinone suggested that it is generated from a (partially cyclized) tridecaketide intermediate condensed to an (N-methyl)-enduracididine, followed by formation of ring F. Oxidation at C-5, C-13, and C-14 and the three O- methylations might precede or follow ring F formation. To search for the enduracyclinone BGC, we scanned a draft genome sequence of Nonomuraea sp. ID40491, using the antiSMASH platform (https://antismash.secondarymetabolites.org) for the presence of an aromatic polyketide gene cluster associated with genes specifying for l-enduracididine biosynthesis. The likely enduracyclinone (edc) cluster encompasses a 37 kbp segment and includes 35 CDSs. By bioinformatic analysis we could assign a putative role to almost all genes in the cluster and establish its likely boundaries, as depicted in Figure 4 and summarized in Table 2.

Figure 4

Figure 4. Organization of the enduracyclinone biosynthetic genes. The deduced functions are color-coded as indicated and summarized in Table 2. end, enduracididine; mCoA, malonyl-CoA.

High Resolution Image
Download MS PowerPoint Slide
Table 2. Coding DNA Sequences (CDSs) from the edc Cluster of Nonomuraea sp. ID40491 and Proposed Roles in the Pathway
edc CDS size (aa) homologue (strain, accession no.)a identity (%) putative role
Chr_03759 115 Transposase (Nonomuraea coxensis, WP̅026213651) 85 outside cluster
Chr_03760 612 hypothetical protein (Streptomyces sp., CNS335) 68 unknown, outside cluster?
Chr_03761 219 DNA repair protein (Nonomuraea sp. NBRC 110462, WP̅055503593.1) 77 unknown, outside cluster?
Chr_03762 350 O-methyltransferase (Micromonospora echinospora, ADB23385) 45 cyclase-methyltransferase
Chr_03763 219 putative leucyldemethylblasticidin S guanidine methyltransferase (Streptomyces griseochromogenes, AAP03126.1) 51 methyltransferase
Chr_03764 448 PdmP1, biotin carboxylase (Actinomadura hibisca, ABM21735.1) 61 subunit of acetyl carboxylase
Chr_03765 156 biotin carboxyl carrier protein of acetyl-CoA carboxylase (Streptomyces lydicus, AJT61720.1) 47 subunit of acetyl carboxylase
Chr_03766 542 acetyl carboxylase (Streptomyces sp. R1128, AAG30193.1) 60 subunit of acetyl carboxylase
Chr_03767 191 GrhU, monooxygenase (Streptomyces sp. JP95, AAM33683.1) 53 monooxygenase
Chr_03768 154 putative monooxygenase (Streptomyces flavogriseus, ADE22312.1) 39 monooxygenase
Chr_03769 150 RubF, putative polyketide cyclase/reductase (Streptomyces collinus, AAG03070.2) 67 cyclase/reductase
Chr_03770 107 putative cyclase (Streptomyces collinus, AAG03065.2) 71 cyclase
Chr_03771 372 PLP-dependent aminotransferase MppQ (Streptomyces hygroscopicus, AAU34210) 54 enduracididine biosynthesis
Chr_03772 374 enduracididine biosynthesis enzyme MppP (Streptomyces hygroscopicus, AAU34209) 63 enduracididine biosynthesis
Chr_03773 613 PdmN, asparagine synthetase (Actinomadura hibisca, ABK58686.1) 50 enduracididine-polyketide amide synthase
Chr_03774 249 ABC transporter (Micromonospora sp., ALA09377.1) 58 export
Chr_03775 649 Sio5, ABC transporter (Streptomyces sioyaensis, ACN80636.1) 30 transporter
Chr_03776 217 Azi47, DNA-binding response regulator (Streptomyces sahachiroi, ABY83185.1) 63 DNA-binding response regulator
Chr_03777 445 regulatory protein D (Actinoplanes friuliensis, CAM56777.1) 44 regulator
Chr_03778 270 conserved hypothetical protein MppR (Streptomyces hygroscopicus, AAU34211.1) 65 enduracididine biosynthesis
Chr_03779 317 EpaU, cytochrome oxidase subunit II (Kitasatospora sp. HKI 714, AHW81480.1) 39 oxidase
Chr_03780 419 EpaT, cytochrome ubiquinol oxidase (Kitasatospora sp. HKI 714, AHW81479.1) 56 oxidase
Chr_03781 85 ACP (Streptomyces griseus, CAE17520.1) 62 ACP
Chr_03782 512 putative efflux protein (Streptomyces kanamyceticus, CAF60521.1) 38 transporter
Chr_03783 32 putative protease (Streptomyces olivoviridis, BAN83926.1) 47 unknown
Chr_03784 494 FAD-dependent monoxygenase (Micromonospora echinospora,ADB23401.1) 48 monoxygenase. hydroxylase
Chr_03785 338 putative O-methyltransferase (Streptomyces tendae Tu 4042, CAM34375.1) 49 O-methyltransferase
Chr_03786 498 putative peptide transporter (Streptomyces griseus ATCC 43944, AAQ08913.1) 50 transporter
Chr_03787 393 cytochrome P450 (Streptomyces sp. TA-0256, BAJ52675.1) 53 monoxygenase
Chr_03788 221 LuxR transcriptional regulator (uncultured bacterium, AHX24716.1) 65 regulator
Chr_03789 373 two component system histidine kinase (uncultured bacterium, AHX24717.1) 40 regulator
Chr_03790 137 cyclase (uncultured bacterium, AHX24700.1) 69 polyketide cyclase
Chr_03791 420 polyketide beta-ketoacyl synthase alpha (Streptomyces flavogriseus, ADE22315.1) 77 KSα
Chr_03792 400 Hex23, polyketide beta-ketoacyl synthase beta (Streptosporangium sp. CGMCC 4.7309, AMK51280.1) 66 KSβ
Chr_03793 259 DacT1, DNA-binding response regulator (Dactylosporangium sp. SC14051, AFU65883.1) 49 transcriptional regulator
Chr_03794 514 twin-arginine translocation pathway signal sequence (Kibdelosporangium aridum, SMD27155) 64 outside cluster?
a

Best match observed by BLAST analysis of clusters listed in the MIBIG database of validated biosynthetic gene clusters (37) or from the nonredundant GenBank database. Abbreviations: ACC, acetylCoA carboxylase; ACP, acyl carrier protein; BCCP, biotin carboxylate carrier protein; KSα, type II polyketide synthase β-ketoacyl synthase, alpha subunit; KSβ, type II polyketide synthase β-ketoacyl synthase, beta subunit.

The biosynthesis of l-enduracididine has been established for the mannopeptimycin pathway; it involves MppP, a PLP-dependent aminotransferase proposed to convert l-Arg into 2-oxo-4-hydroxy-5-guanidinovaleric acid, which is then cyclized by MppR and transaminated by MppQ, using l-Ala as amino donor. (24) Proteins showing 81%, 68%, and 75% identity to MppP, MppQ, and MppR, respectively, are encoded by a three-gene cassette (endPQR) in the enduracidine gene cluster. (23) ORFs with 63–62%, 54–56%, and 65–66% identity to MppP/EndP, MppQ/EndQ, and MppR/EndR, respectively, are present in the edc cluster, although only the former two genes are adjacent (Figure 4). The edc cluster encodes a protein (Chr_03773) with 50% identity to PdmN, an asparagine synthase-like enzyme involved in the biosynthesis of pradimicin, a dodecaketide linked through an amide bond to an Ala residue. (26) Thus, Chr_03773 is the likely amino acid ligase attaching (N-methyl)enduracidin to a tridecapolyketide precursor.
Synthesis of the enduracyclinone carbon backbone is expected to require a type II PKS. Accordingly, the edc cluster encodes a ketosynthase, chain length factor (CLF), and acyl carrier protein, although the latter gene is not immediately downstream of the CLF-encoding gene (Figure 4 and Table 2). The edc cluster encodes also three polyketide cyclases, four monooxygenases, two methyltransferases, two oxidases, and a bifunctional cyclase-methyltransferase. The edc cluster also encodes a malonyl-CoA-generating system (the three components of a biotin-dependent carboxylase for generating the malonyl-CoA extender units), recently found also in the paramegnetoquinone gene cluster from Actinoallomurus. (27) In addition, the cluster encodes five regulators, four transporters, and three proteins of unknown function (Figure 4 and Table 2). Final confirmation of the role of the described cluster in enduracyclinone biosynthesis should be obtained by genetic manipulation (e.g., by generation of knockout mutants or by heterologous expression), which was beyond the scope of our work. However, it would also be interesting to analyze the genomes of the other seven producers to check whether they contain the identified cluster.

Biological Activity of Enduracyclinones

Enduracyclinone A (1) showed good activity against staphylococci and streptococci, with MICs ranges of 0.0005–0.03 and 0.25–0.5 μg mL–1, respectively (Table 3). Activity was also observed against enterococci (MICs 2–4 μg mL–1), Clostridium difficile (2 μg mL–1), and Propionibacterium acnes (0.25 μg mL–1). No activity was observed against Mycobacterium smegmatis, Gram-negative bacteria, or Candida albicans. Identical activity against S. aureus ATCC 6538P was obtained for purified compound 1 and for the mixture containing 1 and its des-methyl derivative in a 9:1 ratio, ruling out the possibility that the observed biological activity derived only from peak A′. As expected from its structural novelty, enduracyclinone A (1) was equally active against one strain each of S. aureus and of Staphylococcus hemolyticus with multiple resistance to clinically used antibiotics. Time-kill experiments with two different S. aureus strains indicated a rapid bactericidal activity, with >99.9% killing within 2 to 4 h at 8× MIC. Longer incubations (i.e., 24 h) led to an increase in viable cell counts, comparable to untreated controls (Supplementary Figure S2).
Table 3. Antibacterial Activity of Enduracyclinone A (1), Vancomycin (Van), and Gentamicin (Gen) expressed as MIC values
    MIC (μg mL–1)
straina resistanceb 1 Van Gen
Staphylococcus aureus ATCC 6538P   0.004 0.5 0.5
Staphylococcus aureus ATCC 29213   0.0005 1 0.5
Staphylococcus aureus L3864 MetR 0.03 1 >128
Staphylococcus aureus L3797 MetR, AGsR, CipR, CliR, VanI 0.03 8 64
Staphylococcus hemolyticus L1730   0.03 2 >128
Staphylococcus hemolyticus L1729 MetR TetR, AGsR, CipR 0.015 2 >128
Staphylococcus intermedius ATCC 29663   0.007 1 ≤0.125
Streptococcus pyogenes L49   0.5 0.25 16
Streptococcus pneumoniae ATCC BAA1407 ermB, mefE 0.25 0.5 64
Streptococcus pneumoniae L44   0.25 0.125 8
Enterococcus faecium L568   4 1 32
Enterococcus faecium L569 VanA 2 >128 16
Propionibacterium acnes ATCC 25746   0.25 0.25 2
Clostridium difficile ATCC 17858   2 0.5 128
a

Strains designated with an L prefix are clinical isolates (collected in Italy or USA) from the NAICONS collection. Other strains are from the American Type Culture Collection, USA.

b

The superscript R indicates resistance to methicillin (Met), aminoglycosides (AGs), ciprofloxacin (Cip), clindamycin (Cli), or tetracyclin (Tet); the superscript I indicates intermediate resistance to vancomycin (Van); ermB and mefE indicate the known genetic determinants conferring resistance to macrolides–lincosamides–streptogramins by ribosomal methylation and to macrolides by efflux, respectively. VanA designates vancomycin-inducible resistance to glycopeptides by lipid II modification.

Comparably low MIC values vs Gram-positive bacteria have been reported for some structurally related compounds, such as lysolipin I, (28) cervinomycin, (29) and echinosporamicins. (19) It should be noted that several of these molecules exhibited cytotoxic activity to tumor cell lines at concentrations comparable to or lower than the MIC, (20) e.g., actinoplanone, simaomicin, and xantholipin (30−32) and echinosporamicin-related compounds. (19) When evaluated on the cancer cell line PANC-1 or the non-cancer cell line HEK-293, enduracyclinone A (1) showed only 20% inhibition at 90 μM or an IC50 of 55 μM, respectively (Supplementary Figure S3). Thus, in comparison with the previously mentioned molecules, enduracyclinone A shows little cytotoxicity against the tested cell lines.
As mentioned above, the enduracyclinone-containing extracts were selected for their ≥8-fold higher activity on WT S. aureus than on the corresponding l-form (Supplementary Table S1), indicating that peptidoglycan-devoid cells are less sensitive than the parental cells. When tested against Bacillus subtilis BAU102, a reporter strain that detects most classes of cell wall inhibitors, (13) enduracyclinone A (1) elicited a signal compatible with cell wall inhibition and distinct from that caused by detergents (Supplementary Table S2). We then evaluated the effect of enduracyclinone A (1) on macromolecular synthesis in S. aureus, observing a dose-dependent inhibition of DNA and cell wall biosynthesis, with comparable IC50 values (2 and 5 μg mL–1, respectively). While RNA synthesis was only marginally affected, incorporation of label into proteins appeared to be stimulated by enduracyclinone A (Supplementary Figure S4).
Overall, the results from the l-form assay, the reporter assay, and macromolecular syntheses are consistent with inhibition of cell wall biosynthesis by enduracyclinone A, although DNA synthesis is also likely to be affected. There are few reports on the mechanism of action of structurally related molecules. Lysolipin has been proposed to target bactoprenol-containing molecules and inhibit cell wall biosynthesis, based on inhibition of peptidoglycan synthesis and concomitant accumulation of lipid-bound precursors in B. subtilis. (28) On the basis of its effect on macromolecular syntheses, solute leakage, and reversion assays in S. aureus, cervinomycin has been proposed to interfere with membrane functions by interaction with phospholipids. (33) Inhibition of DNA synthesis, interference with cell cycle regulation, or generation of reactive oxygen species was proposed for the cytotoxic effects of different polycyclic xanthones. (30,31,34) Interestingly, while minosaminomycin (structurally similar to the aminoglycoside kasugamycin) interferes with initiation of protein synthesis, (35) the other enduracididine-containing antibiotics (teixobactin, enduracidine, and mannopeptimycin) inhibit cell wall biosynthesis by binding to lipid II. (36) Thus, it is tempting to speculate that appending a positively charged, rigid amino acid on a flat, hydrophobic skeleton might enhance affinity for cell wall intermediates, endowing enduracyclinone A with a dual mechanism of action.
These potent antibacterial compounds, produced at high levels by at least three different Nonomuraea lineages, had so far apparently escaped detection. This bodes well for discovering new classes of antibacterial agents from actinomycetes.

Experimental Section

ARTICLE SECTIONS
Jump To

General Experimental Procedures

1H and 13C 1D and 2D NMR spectra (COSY, TOCSY, NOESY, HSQC, HMBC, 13C–13C COSY, 1H–15N-HSQC, 1H–15N-HMBC) were measured in DMSO-d6 at 25 °C using a Bruker Avance II 300 MHz spectrometer. The 13C NMR spectrum of compound 1 was acquired on an Agilent (Varian) VNMRS 500 MHz spectrometer. LC-MS analyses were performed with a Dionex UltiMate 3000 (Thermo Scientific) coupled with an LCQ Fleet mass spectrometer equipped with an electrospray interface (ESI) and a tridimensional ion trap. The column was an Atlantis T3 C18 5 μm × 4.6 mm × 50 mm maintained at 40 °C at a flow rate of 0.8 mL min–1. Phases A and B were 0.05% TFA and MeCN, respectively. The gradient was 10%, 10%, 95%, 95%, and 10% phase B at 0, 1, 7, 9, and 10 min, respectively. UV–vis signals (190–600 nm) were acquired using a diode array detector. The m/z range was 110–2000, and the ESI conditions were as follows: spray voltage of 3500 V, capillary temperature of 275 °C, sheath gas flow rate at 35 mL min–1, and auxiliary gas flow rate at 15 mL min–1. HR-MS analyses were performed as a service by the Department of Pharmaceutical Sciences, University of Milan, Italy. HPLC analyses were carried out using a Shimadzu LC-2010AHT equipped with a Merck LiChrosphere100 RP18 LiChroCART column, 5 μm (125 × 4 mm) with detection at 280 nm and oven temperature at 50 °C. Flow rate set at 1 mL min–1. Phases A and B were 0.1% TFA and MeCN, respectively. The gradient used was 10%, 45%, 70%, and 90% phase B at 0, 5, 15, and 17 min, respectively.

Actinomycete Strains and Growth Conditions

Strains were maintained as frozen cultures at −80 °C in the NAICONS strain library. They were cultivated on S1 plates (10) at 30 °C. All Erlenmeyer flasks used for liquid cultures had one baffle. For production of enduracyclinones the microbial content of one S1 plate was scraped and inoculated into 50 mL Erlenmeyer flasks containing 10 mL of medium AF (dextrose monohydrate 20 g L–1, yeast extract 2 g L–1, soybean meal 8 g L–1, NaCl 1 g L–1, and CaCO3 g L–1, pH 7.3). The strains were grown at 30 °C on an orbital shaker at 200 rpm. After 72 h, 5 mL of the culture was transferred into 500 mL Erlenmeyer flasks containing 100 mL of fresh AF medium. After a further 72 h cultivation as above, a 5% inoculum was made into 100 mL of medium INA5 (glycerol 30 g L–1, soybean meal 15 g L–1, CaCO3 5 g L–1, NaCl 2 g L–1, pH 7.2) in 500 mL Erlenmeyer flasks, which were incubated for 168 h under the same conditions described above.

Isotope Labeling

NM medium was ammonium sulfate 1.8 g L–1, KH2PO4 0.15 g L–1, MgSO4·7H2O 0.22 g L–1, TMS 3 mL L–1, vitamin solution 1 mL L–1, and 0.5 M TES pH 7.5 40 mL L–1. [TMS consists of (g L–1) FeSO4·7H2O 5, CuSO4·5H2O 0.39, ZnSO4·7H2O 0.44, MnCl2·4H2O 0.176, NaMoO4·2H2O 0.011, CuCl2·2H2O 0.02; and 50 mL HCl 37%; vitamin solution consists of (g L–1) biotin 0.05, Ca pantothenate 1, nicotinic acid 1, myo-inositol 25, thiamine HCl 1, pyridoxine HCl 1; it was sterilized through a 0.22 μm pore filter and added to the autoclaved medium.] Strain ID40491 from a frozen stock was inoculated (5%) in 50 mL flasks containing 15 mL of NM medium supplemented with 10% glycerol and cultivated 72 h as above. Then, 12 mL of the culture was washed twice with 12 mL of medium NM (by centrifugation and resuspension), and 6 mL of the resuspended mycelium was used to inoculate 100 mL of NM medium supplemented with 1 g L–1 Celtone base powder (>98% 13C- and >98% 15N-labeled, Cambridge Isotope Laboratories). The strain was cultured under the conditions described above for 120 h before metabolite extraction. The average enrichment was calculated using LC-MS analysis (Supplementary Figure S1), which showed a maximum m/z signal of 749 [M + H]+ with an increment of 38 amu with respect to the unlabeled compound. A full labeled compound 1 is expected to have an m/z 751 [M + H]+; thus the enrichment was calculated as 95%.

Metabolite Extraction and Purification

For purification of enduracyclinones, a 600 mL culture was centrifuged (10 min at 1800 rcf), and the resulting mycelium and cleared broth were processed separately. The mycelium was resuspended in water (200 mL final volume) and, after adjusting the pH from 7.9 to 9.7 with 0.5 N NaOH and adding 200 mL of EtOH, shaken for 20 min at RT. After centrifugation (5 min at 1800 rcf), the supernatant was recovered and dried under vacuum. For processing the cleared broth, the pH was adjusted from 7.5 to 5 with 1 N HCl, which led to product precipitation. The pellet was recovered by centrifugation (10 min at 3200 rcf) and resuspended in 60 mL of water. After adjusting the pH to 9.5 with 0.5 N NaOH and adding 60 mL of EtOH, residual debris was removed by centrifugation (10 min at 1800 rcf) and the solvent from the resulting supernatant was removed under reduced pressure.
The crude extracts from mycelium and cleared broth were separately purified on a CombiFlash RF (Teledyne ISCO) medium-pressure chromatography system on a 30 g Biotage SNAP Cartridge KP-C18-HS. Flow was 30 mL min–1, phase A was water with 0.1% TFA, and phase B was acetonitrile. The column was previously conditioned at 5% phase B, gradient to 40% phase B in 2 min, and then 60% phase B in 25 min. Fractions with similar purity were pooled and dried under vacuum, yielding 90 mg of a dark red powder containing compounds 1 and des-methyl-1 in a 9:1 ratio. This powder was used for NMR characterization and for nearly all bioactivity studies. From the same chromatography, an additional 35 mg sample was collected containing compounds 1, 2, and des-methyl 1 in a 5:3:2 ratio. A 2 mg amount of the 9:1 ratio powder was further purified using an LC 2010A-HT liquid chromatography instrument (Shimadzu Corporation) equipped with a LiChrosphere C18 5 μm, 4.6 mm × 100 mm column (Merck). Elution was performed at 1 mL min–1, 50 °C with a multistep program set as follows: 10%, 45%, 70%, 90%, 90%, 10%, and 10% phase B at 0, 15, 17, 20, 21, and 29 min, respectively. Phase A was 0.1% TFA (v/v) in H2O, and phase B was CH3CN. UV detection was set at 270 and 420 nm. About 450 μg of purified compound 1 (enduracyclinone A) was collected and used for MIC evaluation on S. aureus ATCC 6538P.
For purification of the labeled compounds, 20 mL of 0.5 M ammonium acetate (pH 8.8) and 110 mL of EtOH were added to a 200 mL culture, and the suspension was shaken 1 h at RT. After centrifugation (10 min 1800 rcf), the supernatant was recovered, partially concentrated under vacuum to remove EtOH, and acidified to pH 4–4.5 with 1 N HCl. Under these conditions enduracyclinones form a dark red precipitate, which was collected by centrifugation (10 min 1800 rcf) and dried under vacuum, obtaining 5 mg of 95% labeled compounds 1 and des-methyl-1 in a 9:1 ratio.

Enduracyclinone A, 1:

HPLC tR 9.5 min; LC-MS tR 5.93 min UV–vis (0.1% TFA/MeCN, 1:1) λmax 234, 283, 334, and 445 nm; 1H and 13C NMR data, Table 1; ESI(+)MS m/z 711.2 [M + H]+; HRESI(+) MS m/z 711.1942 [M + H]+ (calcd for C36H30N4O12 711.1938).

Enduracyclinone B, 2:

HPLC tR 12 min; LC-MS tR 6.02 min UV–vis (0.1% TFA/MeCN, 1:1) λmax 241, 295, and 425 nm; ESI(+)MS m/z 713.2 [M + H]+; HRESI(+) MS m/z 713.2104 [M + H]+ (calcd for C36H32N4O12 713.2095).

Des-methyl Enduracyclinone A:

HPLC tR 10 min; LC-MS tR 6.48 min UV–vis (0.1% TFA/MeCN, 1:1) λmax 237, 287, 340, and 470 nm; ESI(+)MS m/z 697.2 [M + H]+; HRESI(+) MS m/z 697.1786 [M + H]+ (calcd for C35H28N4O12697.1776).

Chemical Modifications

Reactions were performed on a sample containing 1 and its des-methyl derivative in a 9:1 ratio (designated 1 for simplicity), unless stated otherwise. Amidation: Compound 1 (2 mg) was dissolved in 400 μL of DMF, and 2 μL of N,N-dimethylpropylamine was added adjusting the pH to 8. After adding 2 mg of PyBOP, the mixture was stirred for 1 h at RT. LC-MS analysis showed the disappearance of compound 1 (tR 5.90 min) and the formation of the corresponding amide (tR 4.57 min, m/z 795.2 [M + H]+ and 398 [M + 2H]2+ and λmax at 245, 285, and 539 nm), along with the formation of des-methyl-1 corresponding amide (tR 4.60 min, m/z 781.1 [M + H]+ and 391 [M + 2H]2+ and λmax at 247, 292, and 537 nm). Methylation: To a solution of 1 (1 mg) in 100 μL of MeOH, was added 4 μL of 2 M trimethylsylyldiazomethane in diethyl ether, and the solution stirred at RT for 5 h. LC-MS analysis showed the disappearance of 1 and formation of one peak at 6.18 min with m/z 725.2 [M + H]+ and λmax at 235, 284, 336, and 440 nm, and a second peak at 6.28 min with m/z 711.3 [M + H]+ and λmax at 243, 288, and 432 nm, corresponding to the methyl esters of 1 and of des-methyl-1, respectively. Oxidation: Compounds 1, 2, and des-methyl-1 (2 mg, in a 5:3:2 ratio) were dissolved in 2.5 mL of MeCN/H2O (1:1), and 175 μL of 30% H2O2 was added. After 24 h at RT, LC-MS analysis showed the conversion of compound 2 into 1. Quinone cleavage: Compound 1 (1 mg) was dissolved in 50 μL of MeCN/H2O (1:1), and 100 μL of 30% H2O2 was added. The mixture was heated to 60 °C, and the reaction monitored by LC-MS, which showed the formations of peaks at 5.15, 6.30, and 6.72 min corresponding to m/z [M + H]+ values of 637.0 (ox-1, λmax at 234, 313, and 420 nm), 469.1 (ox-2,major species; λmax at 246, 300, and 430 nm), 455.1 (des-methyl-ox-2, minor species), and 279.2 (ox-3, λmax at 300 nm), respectively.

Biological Assays

All tests were performed on a sample containing 1 and its des-methyl derivative in a 9:1 ratio. MIC for S. aureus ATCC 6538P was determined also for the purified compound 1. Antimicrobial activity of extracts was evaluated by agar diffusion, using extracts obtained by centrifuging (10 min 1800 rcf) a 10 mL culture and extracting the resulting mycelium with 4 mL of EtOH for 1 h at RT with shaking. The EtOH extracts (200 μL, corresponding to 0.5 mL of culture) were dried under vacuum and dissolved in 100 μL of 10% DMSO, and 10 μL was then deposited on 30 mL of Mueller-Hinton agar in a 14.5 mm diameter plate inoculated with 105 CFU/mL S. aureus ATCC 6538P or L3797, scoring the presence of growth inhibition halos after 16 h at 37 °C. Determination of minimal inhibitory concentrations (MIC) was performed as previously described. (10) Time-kill experiments were performed following a previously described procedure. (11) The conditions for using Bacillus subtilis BAU102 to detect cell wall inhibitors or detergents have been previously described. (13)

Effect on Macromolecular Syntheses

The effect on macromolecular synthesis was tested by monitoring the incorporation of labeled precursors (5-[3H]thymidine for DNA, [3H]uridine for RNA, l-[3H]tryptophan for protein and [3H]glucosamine hydrochloride for cell wall synthesis). S. aureus 12ST clinical isolate (P.L. proprietary collection) was grown overnight in 0.2× LB (2 g L–1 peptone, 1 g L–1 yeast extract, and 2 g L–1 NaCl), then diluted 200-fold into the same medium, and grown at 37 °C to an OD600 of 0.2–0.25. This medium can support fast growth while allowing efficient incorporation of labeled precursors (P.L., unpublished data). Cultures were split into four subcultures (80 μL) and added to Eppendorf tubes containing either 10 μL of medium (control) or 10 μL of 1 at 10-fold the final concentrations. After 5 min incubation at 37 °C, 10 μL of radioactively labeled precursors (PerkinElmer), previously diluted to 0.1 μCi μL–1 (1:10), was added as follows: [6-3H]-thymidine, 0.15 μCi/sample; [5,6-3H]-uridine, 0.15 μCi/sample; l-[5-3H(N)]-tryptophan, 0.25 μCi/sample; d-[6-3H(N)]-glucosamine hydrochloride, 0.4 μCi/sample. Samples were incubated for a further 5 min at 37 °C; incorporation was stopped and macromolecules were precipitated by adding 0.9 mL of ice-cold 5% trichloroacetic acid (TCA) and incubated for at least 30 min on ice before being filtered through glass microfiber filters (GF/C, Whatman). Filters were washed with 5 mL of TCA (5%), dried, and counted in a Tricarb 2100 TR liquid scintillation analyzer (PerkinElmer) using the Ultima Gold scintillation cocktail (PerkinElmer). 1 was dissolved at 10 mg mL–1 in 50% DMSO immediately prior to use, and subsequent dilutions were made in 0.2× LB. Maximal DMSO concentrations used in the experiment were 0.5%, which did not affect either bacterial growth or incorporation of labeled markers, as tested in preliminary experiments. As controls for macromolecular synthesis inhibition, we used antibiotics with known mechanisms of action, namely, nalidixc acid (25 μg/mL) for DNA synthesis, rifampicin (2 μg/mL) for RNA synthesis, chloramphenicol (20 μg/mL) for protein synthesis, and vancomycin (1 μg/mL) for cell wall synthesis. In the experimental conditions used, these compounds totally and selectively inhibited their target macromolecular synthesis (data not shown).

DNA Sequences

DNA extraction, sequencing, and analysis of the 16S rRNA gene were performed following published procedures. (38) A draft genome sequence of Nonomuraea ID40491 was generated through Illumina technology by Microbial Genomics and Biotechnology Center for Biotechnology (Universität Bielefeld, Germany). Identification of the biosynthetic gene cluster was performed using the antiSMASH v3.0.1 tool at the default conditions. (39)

Accession Codes

The DNA sequences of the 16S rRNA genes and putative enduracyclinone gene cluster have been deposited in GenBank with accession numbers MF359959–MF359965 (Supplementary Table S2) and MG386284, respectively.

Supporting Information

ARTICLE SECTIONS
Jump To

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jnatprod.8b00354.

  • Experimental Section; characteristics of enduracyclinone-producing strains; reporter gene induction assay; time-kill data; cytotoxicity data; macromolecular syntheses inhibition data; 13C–15N enrichment data; NMR spectra (PDF)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

ARTICLE SECTIONS
Jump To
  • Corresponding Author
  • Authors
    • Alice Bernasconi - NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    • Marianna Iorio - NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy;  Orcidhttp://orcid.org/0000-0001-8669-5875
    • Cristina Brunati - KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    • Margherita Sosio - NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy;  KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    • Laura Campochiaro - NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy
    • Paolo Landini - Bioscience Department, Università degli Studi di Milano, Via Celoria 2, 20122 Milano, Italy
    • Sonia I. Maffioli - NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy;  KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
    • Stefano Donadio - NAICONS Srl, Viale Ortles 22/4, 20139 Milano, Italy;  KtedoGen Srl, Viale Ortles 22/4, 20139 Milano, Italy
  • Notes
    The authors declare the following competing financial interest(s): P.M., A.B., M.I., C.B., M.S., S.M., and S.D. are employees and/or shareholders of NAICONS and/or KtedoGen.

Acknowledgments

ARTICLE SECTIONS
Jump To

This work received support from the European Commission’s Horizon 2020 programme under grant agreement 664588 (NOMORFILM project) and from MiUR-Regione Lombardia. We thank I. Biunno and M. Cattaneo (IRGB-CNR, Milan) for the cytotoxicity test, H.-G. Sahl (University of Bonn) for helpful advice, and R. Fattori (IFOM, Milan) for 1D-13C NMR experiment.

References

ARTICLE SECTIONS
Jump To

This article references 39 other publications.

  1. 1
    Moloney, M. G. Trends Pharmacol. Sci. 2016, 37, 689– 701,  DOI: 10.1016/j.tips.2016.05.001
    Google Scholar
    1
    Natural Products as a Source for Novel Antibiotics
    Moloney, Mark G.
    Trends in Pharmacological Sciences (2016), 37 (8), 689-701CODEN: TPHSDY; ISSN:0165-6147. (Elsevier Ltd.)
    A review. Natural products have historically been of crucial importance in the identification and development of antibacterial agents. Interest in these systems has waned in recent years, but the rapid emergence of resistant bacterial strains has forced their re-evaluation as a route to identify novel chem. skeletons with antibacterial activity for elaboration in drug development. This overview examines the current situation, highlights new natural product systems which have been found, together with re-examn. of some old ones, and new technologies for their identification. While natural products certainly have the potential to re-emerge as a key start-point in antibacterial drug discovery, reports of new or reinvestigated structures need to be supported with sufficient quality chem. (soly., stability), biochem. (including toxicity in particular, along with target information) and microbiol. [min. inhibitory concn. (MIC) and resistance frequency] validation data to assist in the identification of promising hit structures and to avoid wasted effort from trawling over already cultivated territory. This is particularly important in a resource-limited research environment.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XotF2rtrw%253D&md5=091645e56653a4d8d8d43eccad532c00
  2. 2
    Brown, E. D.; Wright, G. D. Nature 2016, 529, 336– 343,  DOI: 10.1038/nature17042
    Google Scholar
    2
    Antibacterial drug discovery in the resistance era
    Brown, Eric D.; Wright, Gerard D.
    Nature (London, United Kingdom) (2016), 529 (7586), 336-343CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    A review. The looming antibiotic resistance crisis has penetrated the consciousness of clinicians, researchers, policymakers, politicians and the public at large. The evolution and widespread distribution of antibiotic resistance elements in bacterial pathogens has made diseases that were once easily treatable deadly again. Unfortunately, accompanying the rise in global resistance is a failure in antibacterial drug discovery. Lessons from the history of antibiotic discovery and fresh understanding of antibiotic action and the cell biol. of microorganisms have the potential to deliver twenty-first century medicines that are able to control infection in the resistance era.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht1Oisro%253D&md5=62e0454601a242db039e60d77be26406
  3. 3
    Bumann, D. Curr. Opin. Microbiol. 2008, 11, 387– 392,  DOI: 10.1016/j.mib.2008.08.002
    Google Scholar
    3
    Has nature already identified all useful antibacterial targets?
    Bumann, Dirk
    Current Opinion in Microbiology (2008), 11 (5), 387-392CODEN: COMIF7; ISSN:1369-5274. (Elsevier B.V.)
    A review. Novel antimicrobial targets are urgently needed to overcome rising antibiotic resistance of important human pathogens. However, evidence from previous antimicrobial screenings, in silico anal., and exptl. target evaluation suggests that the no. of novel bacterial broad-spectrum targets might be severely limited. This is because of the poor conservation of genes among diverse bacterial pathogens, partial functional redundancy and nutrient-rich host environments. Remaining opportunities under these circumstances include the development of narrow-spectrum antibiotics against specific pathogens and the exploration of target combinations.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlGgsL%252FL&md5=1a188819439c63fc02e061163c8d718b
  4. 4
    Demain, A. L. J. Ind. Microbiol. Biotechnol. 2014, 41, 185– 201,  DOI: 10.1007/s10295-013-1325-z
    Google Scholar
    4
    Importance of microbial natural products and the need to revitalize their discovery
    Demain, Arnold L.
    Journal of Industrial Microbiology & Biotechnology (2014), 41 (2), 185-201CODEN: JIMBFL; ISSN:1367-5435. (Springer)
    A review. Microbes are the leading producers of useful natural products. Natural products from microbes and plants make excellent drugs. Significant portions of the microbial genomes are devoted to prodn. of these useful secondary metabolites. A single microbe can make a no. of secondary metabolites, as high as 50 compds. The most useful products include antibiotics, anticancer agents, immunosuppressants, but products for many other applications, e.g., antivirals, anthelmintics, enzyme inhibitors, nutraceuticals, polymers, surfactants, bioherbicides, and vaccines were commercialized. Unfortunately, due to the decrease in natural product discovery efforts, drug discovery has decreased in the past 20 years. The reasons include excessive costs for clin. trials, too short a window before the products become generics, difficulty in discovery of antibiotics against resistant organisms, and short treatment times by patients for products such as antibiotics. Despite these difficulties, technol. to discover new drugs has advanced, e.g., combinatorial chem. of natural product scaffolds, discoveries in biodiversity, genome mining, and systems biol. Of great help would be government extension of the time before products become generic.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtl2qtrrI&md5=657e82af420b3e01942df70b6f691c59
  5. 5
    Newman, D. J.; Cragg, G. M. J. Nat. Prod. 2012, 75, 311– 335,  DOI: 10.1021/np200906s
    Google Scholar
    5
    Natural Products As Sources of New Drugs over the 30 Years from 1981 to 2010
    Newman, David J.; Cragg, Gordon M.
    Journal of Natural Products (2012), 75 (3), 311-335CODEN: JNPRDF; ISSN:0163-3864. (American Chemical Society-American Society of Pharmacognosy)
    This review is an updated and expanded version of the three prior reviews that were published in this journal in 1997, 2003, and 2007. In the case of all approved therapeutic agents, the time frame has been extended to cover the 30 years from Jan. 1, 1981, to Dec. 31, 2010, for all diseases worldwide, and from 1950 (earliest so far identified) to Dec. 2010 for all approved antitumor drugs worldwide. We have continued to utilize our secondary subdivision of a "natural product mimic" or "NM" to join the original primary divisions and have added a new designation, "natural product botanical" or "NB", to cover those botanical "defined mixts." that have now been recognized as drug entities by the FDA and similar organizations. From the data presented, the utility of natural products as sources of novel structures, but not necessarily the final drug entity, is still alive and well. Thus, in the area of cancer, over the time frame from around the 1940s to date, of the 175 small mols., 131, or 74.8%, are other than "S" (synthetic), with 85, or 48.6%, actually being either natural products or directly derived therefrom. In other areas, the influence of natural product structures is quite marked, with, as expected from prior information, the anti-infective area being dependent on natural products and their structures. Although combinatorial chem. techniques have succeeded as methods of optimizing structures and have been used very successfully in the optimization of many recently approved agents, we are able to identify only one de novo combinatorial compd. approved as a drug in this 30-yr time frame. We wish to draw the attention of readers to the rapidly evolving recognition that a significant no. of natural product drugs/leads are actually produced by microbes and/or microbial interactions with the "host from whence it was isolated", and therefore we consider that this area of natural product research should be expanded significantly.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XitVeku78%253D&md5=395ac7378f07d122a5789d7b440f858d
  6. 6
    Ling, L. L.; Schneider, T.; Peoples, A. J.; Spoering, A. L.; Engels, I.; Conlon, B. P.; Mueller, A.; Schaberle, T. F.; Hughes, D. E.; Epstein, S.; Jones, M.; Lazarides, L.; Steadman, V. A.; Cohen, D. R.; Felix, C. R.; Fetterman, K. A.; Millet, W. P.; Nitti, A. G.; Zullo, A. M.; Chen, C.; Lewis, K. Nature 2015, 517, 455– 459,  DOI: 10.1038/nature14098
    Google Scholar
    6
    A new antibiotic kills pathogens without detectable resistance
    Ling, Losee L.; Schneider, Tanja; Peoples, Aaron J.; Spoering, Amy L.; Engels, Ina; Conlon, Brian P.; Mueller, Anna; Schaberle, Till F.; Hughes, Dallas E.; Epstein, Slava; Jones, Michael; Lazarides, Linos; Steadman, Victoria A.; Cohen, Douglas R.; Felix, Cintia R.; Fetterman, K. Ashley; Millett, William P.; Nitti, Anthony G.; Zullo, Ashley M.; Chen, Chao; Lewis, Kim
    Nature (London, United Kingdom) (2015), 517 (7535), 455-459CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    Antibiotic resistance is spreading faster than the introduction of new compds. into clin. practice, causing a public health crisis. Most antibiotics were produced by screening soil microorganisms, but this limited resource of cultivable bacteria was overmined by the 1960s. Synthetic approaches to produce antibiotics have been unable to replace this platform. Uncultured bacteria make up approx. 99% of all species in external environments, and are an untapped source of new antibiotics. We developed several methods to grow uncultured organisms by cultivation in situ or by using specific growth factors. Here we report a new antibiotic that we term teixobactin, discovered in a screen of uncultured bacteria. Teixobactin inhibits cell wall synthesis by binding to a highly conserved motif of lipid II (precursor of peptidoglycan) and lipid III (precursor of cell wall teichoic acid). We did not obtain any mutants of Staphylococcus aureus or Mycobacterium tuberculosis resistant to teixobactin. The properties of this compd. suggest a path towards developing antibiotics that are likely to avoid development of resistance.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFOju7w%253D&md5=27e302d7d44a549a91aa52113c3b4ad8
  7. 7
    Maffioli, S. I.; Zhang, Y.; Degen, D.; Carzaniga, T.; Del Gatto, G.; Serina, S.; Monciardini, P.; Mazzetti, C.; Guglierame, P.; Candiani, G.; Chiriac, A. I.; Facchetti, G.; Kaltofen, P.; Sahl, H. G.; Dehò, G.; Donadio, S.; Ebright, R. H. Cell 2017, 169, 1240– 1248e1223,  DOI: 10.1016/j.cell.2017.05.042
    Google Scholar
    7
    Antibacterial Nucleoside-Analog Inhibitor of Bacterial RNA Polymerase
    Maffioli, Sonia I.; Zhang, Yu; Degen, David; Carzaniga, Thomas; Del Gatto, Giancarlo; Serina, Stefania; Monciardini, Paolo; Mazzetti, Carlo; Guglierame, Paola; Candiani, Gianpaolo; Chiriac, Alina Iulia; Facchetti, Giuseppe; Kaltofen, Petra; Sahl, Hans-Georg; Deho, Gianni; Donadio, Stefano; Ebright, Richard H.
    Cell (Cambridge, MA, United States) (2017), 169 (7), 1240-1248.e23CODEN: CELLB5; ISSN:0092-8674. (Cell Press)
    Drug-resistant bacterial pathogens pose an urgent public-health crisis. Here, we report the discovery, from microbial-ext. screening, of a nucleoside-analog inhibitor that inhibits bacterial RNA polymerase (RNAP) and exhibits antibacterial activity against drug-resistant bacterial pathogens: pseudouridimycin (PUM). PUM is a natural product comprising a formamidinylated, N-hydroxylated Gly-Gln dipeptide conjugated to 6'-amino-pseudouridine. PUM potently and selectively inhibits bacterial RNAP in vitro, inhibits bacterial growth in culture, and clears infection in a mouse model of Streptococcus pyogenes peritonitis. PUM inhibits RNAP through a binding site on RNAP (the NTP addn. site) and mechanism (competition with UTP for occupancy of the NTP addn. site) that differ from those of the RNAP inhibitor and current antibacterial drug rifampin (Rif). PUM exhibits additive antibacterial activity when co-administered with Rif, exhibits no cross-resistance with Rif, and exhibits a spontaneous resistance rate an order-of-magnitude lower than that of Rif. PUM is a highly promising lead for antibacterial therapy.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVWrtrnI&md5=037230d61bb316927bda72308a7a7656
  8. 8
    Monciardini, P.; Iorio, M.; Maffioli, S.; Sosio, M.; Donadio, S. Microb. Biotechnol. 2014, 7, 209– 220,  DOI: 10.1111/1751-7915.12123
    Google Scholar
    8
    Discovering new bioactive molecules from microbial sources
    Monciardini, Paolo; Iorio, Marianna; Maffioli, Sonia; Sosio, Margherita; Donadio, Stefano
    Microbial Biotechnology (2014), 7 (3), 209-220CODEN: MBIIB2; ISSN:1751-7915. (Wiley-Blackwell)
    A review. Summary : There is an increased need for new drug leads to treat diseases in humans, animals and plants. A dramatic example is represented by the need for novel and more effective antibiotics to combat multidrug-resistant microbial pathogens. Natural products represent a major source of approved drugs and still play an important role in supplying chem. diversity, despite a decreased interest by large pharmaceutical companies. Novel approaches must be implemented to decrease the chances of rediscovering the tens of thousands of known natural products. In this review, we present an overview of natural product screening, focusing particularly on microbial products. Different approaches can be implemented to increase the probability of finding new bioactive mols. We thus present the rationale and selected examples of the use of hypersensitive assays; of accessing unexplored microorganisms, including the metagenome; and of genome mining. We then focus our attention on the technol. platform that we are currently using, consisting of approx. 70 000 microbial strains, mostly actinomycetes and filamentous fungi, and discuss about high-quality screening in the search for bioactive mols. Finally, two case studies are discussed, including the spark that arose interest in the compd.: in the case of orthoformimycin, the novel mechanism of action predicted a novel structural class; in the case of NAI-112, structural similarity pointed out to a possible in vivo activity. Both predictions were then exptl. confirmed.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmtVCjs7Y%253D&md5=35e0a536376282ad4bc3b34f26f2a094
  9. 9
    Jabes, D.; Donadio, S. Methods Mol. Biol. 2010, 618, 31– 45,  DOI: 10.1007/978-1-60761-594-1_3
    Google Scholar
    9
    Strategies for the isolation and characterization of antibacterial lantibiotics
    Jabes, Daniela; Donadio, Stefano
    Methods in Molecular Biology (Totowa, NJ, United States) (2010), 618 (Antimicrobial Peptides), 31-45CODEN: MMBIED; ISSN:1064-3745. (Humana Press Inc.)
    Lantibiotics are biol. active peptides produced by several strains from the phyla Firmicutes and Actinobacteria. They are ribosomally synthesized and undergo posttranslational modifications that endow them with the characteristic (methyl)-lanthionine residues. As a result, lantibiotics contain a variable no. of rings, each carrying one thioether link. Many lantibiotics inhibit growth of Gram-pos. bacterial strains by interfering with peptidoglycan formation. Because they bind to the key intermediate lipid II at a site not affected by clin. used antibiotics, they are effective against multidrug-resistant strains. We describe a bioassay-based method suitable for finding antibacterial lantibiotics from actinomycete strains and provide selected procedures for characterizing newly discovered lantibiotics for their antibacterial properties.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtVSlu73F&md5=44d90108cf44a26d7dc10d41f0bc057f
  10. 10
    Simone, M.; Monciardini, P.; Gaspari, E.; Donadio, S.; Maffioli, S. I. J. Antibiot. 2013, 66, 73– 78,  DOI: 10.1038/ja.2012.92
    Google Scholar
    There is no corresponding record for this reference.
  11. 11
    Maffioli, S. I.; Monciardini, P.; Catacchio, B.; Mazzetti, C.; Münch, D.; Brunati, C.; Sahl, H. G.; Donadio, S. ACS Chem. Biol. 2015, 10, 1034– 1042,  DOI: 10.1021/cb500878h
    Google Scholar
    There is no corresponding record for this reference.
  12. 12
    Iorio, M.; Sasso, O.; Maffioli, S. I.; Bertorelli, R.; Monciardini, P.; Sosio, M.; Bonezzi, F.; Summa, M.; Brunati, C.; Bordoni, R.; Corti, G.; Tarozzo, G.; Piomelli, D.; Reggiani, A.; Donadio, S. ACS Chem. Biol. 2014, 9, 398– 404,  DOI: 10.1021/cb400692w
    Google Scholar
    There is no corresponding record for this reference.
  13. 13
    De Pascale, G.; Grigoriadou, C.; Losi, D.; Ciciliato, I.; Sosio, M.; Donadio, S. J. Appl. Microbiol. 2007, 103, 133– 140,  DOI: 10.1111/j.1365-2672.2006.03231.x
    Google Scholar
    13
    Validation for high-throughput screening of a VanRS-based reporter gene assay for bacterial cell wall inhibitors
    De Pascale, G.; Grigoriadou, C.; Losi, D.; Ciciliato, I.; Sosio, M.; Donadio, S.
    Journal of Applied Microbiology (2007), 103 (1), 133-140CODEN: JAMIFK; ISSN:1364-5072. (Blackwell Publishing Ltd.)
    The present study was undertaken to validate, for antibiotic discovery, a reporter gene assay based on a Bacillus subtilis strain expressing the Enterococcus faecium vanRS genes and a vanH-lacZ fusion, which produced β-galactosidase activity in the presence of cell wall inhibitors (CWI) and lysozyme. The reporter assay was miniaturized, automated and validated with antibiotics and tested against portions of chem. and microbial ext. libraries. The assay is simple, fast and reproducible and can detect all CWI, sometimes at concns. lower than those necessary to inhibit bacterial growth. However, some membrane-interfering compds. also generate comparable signals. While most CWI elicit a signal that is transcription-dependent and abolished in an osmoprotective medium, transcription is not required for β-galactosidase activity brought about by the membrane-interfering compds. At least two distinct mechanisms appear to lead to enzymic activity in the reporter strain. Effective counterscreens can be designed to discard the undesired classes of compds. Extensive validation is required before introducing a reporter assay in high-throughput screening. However, the ease of operation and manipulation makes the reporter assays powerful tools for antibiotic discovery.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXovVOqtr8%253D&md5=b0619f682170c6255477763190b62a69
  14. 14
    Gerber, N. N.; Lechevalier, M. P. Can. J. Chem. 1984, 62, 2818– 2821,  DOI: 10.1139/v84-477
    Google Scholar
    There is no corresponding record for this reference.
  15. 15
    Rickards, R. W. J. Antibiot. 1989, 42, 336– 339,  DOI: 10.7164/antibiotics.42.336
    Google Scholar
    There is no corresponding record for this reference.
  16. 16
    Ogawa, H.; Natori, S. Chem. Pharm. Bull. 1968, 16, 1709– 1720,  DOI: 10.1248/cpb.16.1709
    Google Scholar
    There is no corresponding record for this reference.
  17. 17
    Cameron, D. W.; Cromartie, R. I. T.; Kingston, D. G. I.; Todd, L. J. Chem. Soc. 1964, 0, 51– 61,  DOI: 10.1039/JR9640000051
    Google Scholar
    17
    Coloring matters of the aphididae. XVII. The structure and absolute stereochemistry of the protoaphins
    Cameron, D. W.; Cromartie, R. I. T.; Kingston, D. G. I.; Todd, Lord
    Journal of the Chemical Society (1964), (Jan.), 51-61CODEN: JCSOA9; ISSN:0368-1769.
    Structures (I) and (II) (Gl = glucose moiety) are proposed for protoaphins-fb and -sl, resp. On mild redn., a process involving fission of an activated 1,1'-binaphthyl system, each aphin yields a mixt. of a 5,7-dihydroxy-1,4-naphthoquinone and the glucoside of a 1,3,8-naphthalenetriol. The quinone A obtained from the -fb isomer differs from that (A') of the -sl isomer, but the same glucoside B, which can be converted into quinone A, is obtained from each. Oxidn. of quinones A and A' yields the same DD(+)-dilactic acid and this dets. both structure and abs. configuration of the nonaromatic portions of the mols. The two protoaphins differ from one another in the configuration at one center of asymmetry only.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXjvVOgsA%253D%253D&md5=141bae63f88c85a12afb37124b689777
  18. 18
    He, H.; Yang, H. Y.; Luckman, S. W.; Bernan, V. S.; Tsai, G.; Roll, D. M.; Carter, G. T. Helv. Chim. Acta 2004, 87, 1385– 1391,  DOI: 10.1002/hlca.200490126
    Google Scholar
    There is no corresponding record for this reference.
  19. 19
    Banskota, A. H.; Aouidate, M.; Sørensen, D.; Ibrahim, A.; Piraee, M.; Zazopoulos, E.; Alarco, A. M.; Gourdeau, H.; Mellon, C.; Farnet, C. M.; Falardeau, P.; McAlpine, J. B. J. Antibiot. 2009, 62, 565– 570,  DOI: 10.1038/ja.2009.77
    Google Scholar
    There is no corresponding record for this reference.
  20. 20
    Winter, D. K.; Sloman, D. L.; Porco, J. A. Nat. Prod. Rep. 2013, 30, 382– 391,  DOI: 10.1039/c3np20122h
    Google Scholar
    20
    Polycyclic xanthone natural products: structure, biological activity and chemical synthesis
    Winter, Dana K.; Sloman, David L.; Porco, John A, Jr.
    Natural Product Reports (2013), 30 (3), 382-391CODEN: NPRRDF; ISSN:0265-0568. (Royal Society of Chemistry)
    A review. Polycyclic xanthone natural products are a family of polyketides which are characterized by highly oxygenated, angular hexacyclic frameworks. In the last decade, this novel class of mols. has attracted noticeable attention from the synthetic and biol. communities due to emerging reports of their potential use as antitumor agents. The aim of this article is to highlight the most recent developments of this subset of the xanthone family by detailing the innate challenges of the construction of this class of natural products, new synthetic approaches, and pharmacol. data.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXisVKqu70%253D&md5=2bd2518979ea526bef54a38d3c4061fe
  21. 21
    Aoyama, T.; Kojima, F.; Abe, F.; Muraoka, Y.; Naganawa, H.; Takeuchi, T.; Aoyagi, T. J. Antibiot. 1993, 46, 914– 920,  DOI: 10.7164/antibiotics.46.914
    Google Scholar
    21
    Bequinostatins A and B, new inhibitors of glutathione S-transferase, produced by Streptomyces sp. MI384-DF12: production, isolation, structure determination and biological activities
    Aoyama, Takayuki; Kojima, Fukiko; Abe, Fuminori; Muraoka, Yasuhiko; Naganawa, Hiroshi; Takeuchi, Tomio; Aoyagi, Takaaki
    Journal of Antibiotics (1993), 46 (6), 914-20CODEN: JANTAJ; ISSN:0021-8820.
    New benzo[a]naphthacenequinone metabolites, designated bequinostatins A and B (I and II), were isolated from the culture broth of the benastatin-producing strain Streptomyces sp. MI384-DF12. The structures of bequinostatins A and B were detd. by spectral analyses to be 5,6,8,13-tetrahydro-1,6,7,9,11-pentahydroxy-8,13-dioxo-3-pentylbenzo[a]naphthacene-2-carboxylic acid and 2-decarboxybequinostatin A, resp. Bequinostatin A showed considerable inhibitory activity against human pi class glutathione S-transferase.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXhtVWgsL8%253D&md5=4e67c9eb2bc60e316c620fbeb5f6c53f
  22. 22
    Atkinson, D. J.; Naysmith, B. J.; Furkert, D. P.; Brimble, M. A. Beilstein J. Org. Chem. 2016, 12, 2325– 2342,  DOI: 10.3762/bjoc.12.226
    Google Scholar
    22
    Enduracididine, a rare amino acid component of peptide antibiotics: Natural products and synthesis
    Atkinson, Darcy J.; Naysmith, Briar J.; Furkert, Daniel P.; Brimble, Margaret A.
    Beilstein Journal of Organic Chemistry (2016), 12 (), 2325-2342CODEN: BJOCBH; ISSN:1860-5397. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)
    A review. Rising resistance to current clin. antibacterial agents is an imminent threat to global public health and highlights the demand for new lead compds. for drug discovery. One such potential lead compd., the peptide antibiotic teixobactin, was recently isolated from an uncultured bacterial source, and demonstrates remarkably high potency against a wide range of resistant pathogens without apparent development of resistance. A rare amino acid residue component of teixobactin, enduracididine, is only known to occur in a small no. of natural products that also possess promising antibiotic activity. This review highlights the presence of enduracididine in natural products, its biosynthesis together with a review of analogs of enduracididine. Reported synthetic approaches to the cyclic guanidine structure of enduracididine are discussed, illustrating the challenges encountered to date in the development of efficient synthetic routes to facilitate drug discovery efforts inspired by the discovery of teixobactin.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsVyjsbo%253D&md5=64fd7a0bab40306e979fc4ffae919138
  23. 23
    Yin, X.; Zabriskie, T. M. Microbiology 2006, 152, 2969– 2983,  DOI: 10.1099/mic.0.29043-0
    Google Scholar
    There is no corresponding record for this reference.
  24. 24
    Han, L.; Schwabacher, A. W.; Moran, G. R.; Silvaggi, N. R. Biochemistry 2015, 54, 7029– 7040,  DOI: 10.1021/acs.biochem.5b01016
    Google Scholar
    24
    Streptomyces wadayamensis MppP Is a Pyridoxal 5'-Phosphate-Dependent L-Arginine α-Deaminase, γ-Hydroxylase in the Enduracididine Biosynthetic Pathway
    Han, Lanlan; Schwabacher, Alan W.; Moran, Graham R.; Silvaggi, Nicholas R.
    Biochemistry (2015), 54 (47), 7029-7040CODEN: BICHAW; ISSN:0006-2960. (American Chemical Society)
    L-Enduracididine (L-End) is a nonproteinogenic amino acid found in a no. of bioactive peptides, including the antibiotics teixobactin, enduracidin, and mannopeptimycin. The potent activity of these compds. against antibiotic-resistant pathogens like MRSA and their novel mode of action have garnered considerable interest for the development of these peptides into clin. relevant antibiotics. This goal has been hampered, at least in part, by the fact that L-End is difficult to synthesize and not currently com. available. We have begun to elucidate the biosynthetic pathway of this unusual building block. In mannopeptimycin-producing strains, like Streptomyces wadayamensis, L-End is produced from L-Arg by the action of three enzymes: MppP, MppQ, and MppR. Herein, we report the structural and functional characterization of MppP. This pyridoxal 5'-phosphate (PLP)-dependent enzyme was predicted to be a fold type I aminotransferase on the basis of sequence anal. We show that MppP is actually the first example of a PLP-dependent hydroxylase that catalyzes a reaction of L-Arg with dioxygen to yield a mixt. of 2-oxo-4-hydroxy-5-guanidinovaleric acid and 2-oxo-5-guanidinovaleric acid in a 1.7:1 ratio. The structure of MppP with PLP bound to the catalytic lysine residue (Lys221) shows that, while the tertiary structure is very similar to those of the well-studied aminotransferases, there are differences in the arrangement of active site residues around the cofactor that likely account for the unusual activity of this enzyme. The structure of MppP with the substrate analog D-Arg bound shows how the enzyme binds its substrate and indicates why D-Arg is not a substrate. On the basis of this work and previous work with MppR, we propose a plausible biosynthetic scheme for L-End.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslykur7M&md5=9ea1af83bf7f5dc68866544056b62c23
  25. 25
    Magarvey, N. A.; Haltli, B.; He, M.; Greenstein, M.; Hucul, J. A. Antimicrob. Agents Chemother. 2006, 50, 2167– 2177,  DOI: 10.1128/AAC.01545-05
    Google Scholar
    25
    Biosynthetic pathway for mannopeptimycins, lipoglycopeptide antibiotics active against drug-resistant Gram-positive pathogens
    Magarvey, Nathan A.; Haltli, Brad; He, Min; Greenstein, Michael; Hucul, John A.
    Antimicrobial Agents and Chemotherapy (2006), 50 (6), 2167-2177CODEN: AMACCQ; ISSN:0066-4804. (American Society for Microbiology)
    The mannopeptimycins are a novel class of lipoglycopeptide antibiotics active against multidrug-resistant pathogens with potential as clin. useful antibacterials. This report is the first to describe the biosynthesis of this novel class of mannosylated lipoglycopeptides. Included here are the cloning, sequencing, annotation, and manipulation of the mannopeptimycin biosynthetic gene cluster from Streptomyces hygroscopicus NRRL 30439. Encoded by genes within the mannopeptimycin biosynthetic gene cluster are enzymes responsible for the generation of the hexapeptide core (nonribosomal peptide synthetases [NRPS]) and tailoring reactions (mannosylation, isovalerylation, hydroxylation, and methylation). The NRPS system is noncanonical in that it has six modules utilizing only five amino acid-specific adenylation domains and it lacks a prototypical NRPS macrocyclizing thioesterase domain. Anal. of the mannopeptimycin gene cluster and its engineering has elucidated the mannopeptimycin biosynthetic pathway and provides the framework to make new and improved mannopeptimycins biosynthetically.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XlsVOiurc%253D&md5=fea95a0f18946cb30891bc9b38361d58
  26. 26
    Zhan, J.; Qiao, K.; Tang, Y. ChemBioChem 2009, 10, 1447– 1452,  DOI: 10.1002/cbic.200900082
    Google Scholar
    There is no corresponding record for this reference.
  27. 27
    Iorio, M.; Cruz, J.; Simone, M.; Bernasconi, A.; Brunati, C.; Sosio, M.; Donadio, S.; Maffioli, S. I. J. Nat. Prod. 2017, 80, 819– 827,  DOI: 10.1021/acs.jnatprod.6b00654
    Google Scholar
    27
    Antibacterial Paramagnetic Quinones from Actinoallomurus
    Iorio, Marianna; Cruz, Joao; Simone, Matteo; Bernasconi, Alice; Brunati, Cristina; Sosio, Margherita; Donadio, Stefano; Maffioli, Sonia I.
    Journal of Natural Products (2017), 80 (4), 819-827CODEN: JNPRDF; ISSN:0163-3864. (American Chemical Society-American Society of Pharmacognosy)
    Four metabolites, designated paramagnetoquinone A (I, R1=OMe, R2=NHCH3), B (I, R1=R2=OMe), C, and D, were isolated from 3 strains belonging to the actinomycete genus Actinoallomurus. A and B showed potent antibacterial activity with MIC values <0.015 μg/mL against Gram-pos. pathogens, including antibiotic-resistant strains. Since compds. A and B were NMR-silent due to the presence of an oxygen radical, structure elucidation was achieved through a combination of derivatizations, oxidns., and anal. of 13C-labeled compds. The paramagnetoquinones share the same carbon scaffold as tetracenomycin but carry 2 quinones and a 5-membered lactone fused to the arom. system. B and A are identical except for an unprecedented replacement of a methoxy in B by a methylamino group in A. Related compds. devoid of Me group(s) and of antibacterial activity were isolated from a different Actinoallomurus strain. The likely pmq biosynthetic gene cluster was identified from strain ID145113. While the cluster encodes many of the expected enzymes involved in the formation of arom. polyketides, it also encodes a dedicated ketoacid dehydrogenase complex and an unusual acyl carrier protein transacylase, suggesting that an unusual starter unit might prime the polyketide synthase.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjtVajtLc%253D&md5=80abbea165639e21cc136aa1e1f431da
  28. 28
    Drautz, H.; Keller-Schierlein, W.; Zähner, H. Arch. Microbiol. 1975, 106, 175– 190,  DOI: 10.1007/BF00446521
    Google Scholar
    28
    Metabolic products of microorganisms. 149. Lysolipin I, a new antibiotic from Streptomyces violaceoniger
    Drautz, H.; Keller-Schierlein, W.; Zaehner, H.
    Archives of Microbiology (1975), 106 (3), 175-90CODEN: AMICCW; ISSN:0302-8933.
    From the cultures of S. violaceoniger, strain Tue 96, 2 new lipophilic antibiotics, lysolipin I [59113-57-4] and lysolipid X [59029-83-3] were isolated. The latter one is chem. unstable and is easily transformed to lysolipin I. The deeply yellow lysolipin I has a mol. formula C29H24ClNO11. It was characterized by the ir, uv, H-NMR and 13C-NMR spectra, which make a quinone structure very probable. Lysolipin I is active against gram-pos. and gram-neg. bacteria. However, enterobacteria are only inhibited in high diln., when the membrane permeation is damaged. Lysolipin I acts lytically against bacterial cells. Its activity is decreased by several lipids. The site of action is the biosynthesis of bacterial cell walls, an interaction with the carrier lipid for murein intermediates being probable.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE28Xhslyit7k%253D&md5=1243d24899e44bdde079a6cff15a2bcc
  29. 29
    Nakagawa, A.; Iwai, Y.; Shimizu, H.; Omura, S. J. Antibiot. 1986, 39, 1636– 1638,  DOI: 10.7164/antibiotics.39.1636
    Google Scholar
    There is no corresponding record for this reference.
  30. 30
    Kobayashi, K.; Nishino, C.; Ohya, J.; Sato, S.; Mikawa, T.; Shiobara, Y.; Kodama, M. J. Antibiot. 1988, 41, 741– 750,  DOI: 10.7164/antibiotics.41.741
    Google Scholar
    30
    Actinoplanones C, D, E, F and G, new cytotoxic polycyclic xanthones from Actinoplanes sp
    Kobayashi, Koji; Nishino, Chikao; Ohya, Junichi; Sato, Shigeru; Mikawa, Takashi; Shiobara, Yoshinori; Kodama, Mitsuaki
    Journal of Antibiotics (1988), 41 (6), 741-50CODEN: JANTAJ; ISSN:0021-8820.
    Five new cytotoxic polycyclic xanthones were isolated from the culture broth of Actinoplanes sp. R-304 and were named actinoplanones C, D, E, F, and G. Actinoplanones C and G showed very strong cytotoxicity against HeLa cells at <0.00004 μg/mL dosage (IC50). The structures were varieties of actinoplanone A (I) for the N-2 and C-4 substituents. All or several actinoplanones showed strong antimicrobial activities against bacteria and the rice blast fungus. When tested for cytotoxicity against various tumor cells and for inhibitory effect on HeLa cell macromol. synthesis, I exhibited strong cytotoxicity against the cells and inhibitory action on DNA synthesis.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL1cXltVOnt74%253D&md5=aa58f4ea0023074df4a08fbac085b3d6
  31. 31
    Koizumi, Y.; Tomoda, H.; Kumagai, A.; Zhou, X. P.; Koyota, S.; Sugiyama, T. Cancer Sci. 2009, 100, 322– 326,  DOI: 10.1111/j.1349-7006.2008.01033.x
    Google Scholar
    31
    Simaomicin α, a polycyclic xanthone, induces G1 arrest with suppression of retinoblastoma protein phosphorylation
    Koizumi, Yukio; Tomoda, Hiroshi; Kumagai, Ayako; Zhou, Xiao-ping; Koyota, Souichi; Sugiyama, Toshihiro
    Cancer Science (2009), 100 (2), 322-326CODEN: CSACCM; ISSN:1347-9032. (Wiley-Blackwell)
    Recent progress in cancer biol. research has shown that abnormal proliferation in tumor cells can be attributed to aberrations in cell cycle regulation, esp. in G1 phase. During the course of searching for microbial metabolites that affect cell cycle distribution, we have found that simaomicin α, a polycyclic xanthone antibiotic, arrests the cell cycle at G1 phase. Treatment of T-cell leukemia Jurkat cells with 3 nM simaomicin α induced an increase in the no. of cells in G1 and a decrease in those in G2-M phase. Cell cycle aberrations induced by simaomicin α were also detected in colon adenocarcinoma HCT15 cells. Simaomicin α had antiproliferative activities in various tumor cell lines with 50% inhibitory concn. values in the range of 0.3-19 nM. Furthermore, simaomicin α induced an increase in cellular caspase-3 activity and DNA fragmentation, indicating that simaomicin α promotes apoptosis. The retinoblastoma protein phosphorylation status of simaomicin α-treated cell lysate was lower than that of control cells, suggesting that the target mol. of simaomicin α is in a pathway upstream of retinoblastoma protein phosphorylation. In the course of evaluating polycyclic xanthone antibiotics structurally related to simaomicin α, we also found that cervinomycin A1 stimulated accumulation of treated cells in G1 phase. These results indicate that the polycyclic xanthones, including simaomicin α and cervinomycin A1, may be candidate cancer chemotherapeutic agents.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhvVylsL8%253D&md5=94c3c193912efe7ee1c10ee5696a83cb
  32. 32
    Zhang, W.; Wang, L.; Kong, L.; Wang, T.; Chu, Y.; Deng, Z.; You, D. Chem. Biol. 2012, 19, 422– 432,  DOI: 10.1016/j.chembiol.2012.01.016
    Google Scholar
    32
    Unveiling the post-PKS redox tailoring steps in biosynthesis of the type II polyketide antitumor antibiotic xantholipin
    Zhang, Weike; Wang, Lu; Kong, Lingxin; Wang, Tao; Chu, Yiwen; Deng, Zixin; You, Delin
    Chemistry & Biology (Oxford, United Kingdom) (2012), 19 (3), 422-432CODEN: CBOLE2; ISSN:1074-5521. (Elsevier Ltd.)
    Xantholipin from Streptomyces flavogriseus is a curved hexacyclic arom. polyketide antitumor antibiotic. The entire 52 kb xantholipin (xan) biosynthetic gene cluster was sequenced, and bioinformatic anal. revealed open reading frames encoding type II polyketide synthases, regulators, and polyketide tailoring enzymes. Individual in-frame mutagenesis of five tailoring enzymes lead to the prodn. of nine xantholipin analogs, revealing that the xanthone scaffold formation was catalyzed by the FAD binding monooxygenase XanO4, the δ-lactam formation by the asparagine synthetase homolog XanA, the methylenedioxy bridge generation by the P 450 monooxygenase XanO2 and the hydroxylation of the carbon backbone by the FAD binding monooxygenase XanO5. These findings may also apply to other polycyclic xanthone antibiotics, and they form the basis for genetic engineering of the xantholipin and similar biosynthetic gene clusters for the generation of compds. with improved antitumor activities.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XksFeisLc%253D&md5=db17ce4c8a5192387e112a0dd9890c2f
  33. 33
    Tanaka, H.; Kawakita, K.; Suzuki, H.; Spiri-Nakagawa, P.; Omura, S. J. Antibiot. 1989, 42, 431– 439,  DOI: 10.7164/antibiotics.42.431
    Google Scholar
    There is no corresponding record for this reference.
  34. 34
    Liu, L. L.; He, L. S.; Xu, Y.; Han, Z.; Li, Y. X.; Zhong, J. L.; Guo, X. R.; Zhang, X. X.; Ko, K. M.; Qian, P. Y. Chem. Res. Toxicol. 2013, 26, 1055– 1063,  DOI: 10.1021/tx4000304
    Google Scholar
    There is no corresponding record for this reference.
  35. 35
    Suzukake, K.; Hori, M. J. Antibiot. 1977, 30, 132– 140,  DOI: 10.7164/antibiotics.30.132
    Google Scholar
    There is no corresponding record for this reference.
  36. 36
    Müller, A.; Klöckner, A.; Schneider, T. Nat. Prod. Rep. 2017, 34, 909– 932,  DOI: 10.1039/C7NP00012J
    Google Scholar
    36
    Targeting a cell wall biosynthesis hot spot
    Mueller, Anna; Kloeckner, Anna; Schneider, Tanja
    Natural Product Reports (2017), 34 (7), 909-932CODEN: NPRRDF; ISSN:0265-0568. (Royal Society of Chemistry)
    A review on antibiotics. History points to the bacterial cell wall biosynthetic network as a very effective target for antibiotic intervention, and numerous natural product inhibitors have been discovered. In addn. to the inhibition of enzymes involved in the multistep synthesis of the macromol. layer, in particular, interference with membrane-bound substrates and intermediates essential for the biosynthetic reactions has proven a valuable antibacterial strategy. A prominent target within the peptidoglycan biosynthetic pathway is lipid II, which represents a particular "Achilles' heel" for antibiotic attack, as it is readily accessible on the outside of the cytoplasmic membrane. Lipid II is a unique non-protein target that is one of the structurally most conserved mols. in bacterial cells. Notably, lipid II is more than just a target mol., since sequestration of the cell wall precursor may be combined with addnl. antibiotic activities, such as the disruption of membrane integrity or disintegration of membrane-bound multi-enzyme machineries. Within the membrane bilayer lipid II is likely organized in specific anionic phospholipid patches that form a particular "landing platform" for antibiotics. Nature has invented a variety of different "lipid II binders" of at least 5 chem. classes, and their antibiotic activities can vary substantially depending on the compds.' physicochem. properties, such as amphiphilicity and charge, and thus trigger diverse cellular effects that are decisive for antibiotic activity.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFSls7rP&md5=6876099d28da5efd81da1855f7b8f683
  37. 37
    Medema, M. H.; Kottmann, R.; Yilmaz, P.; Cummings, M.; Biggins, J. B.; Blin, K.; de Bruijn, I.; Chooi, Y. H.; Claesen, J.; Coates, R. C.; Cruz-Morales, P.; Duddela, S.; Düsterhus, S.; Edwards, D. J.; Fewer, D. P.; Garg, N.; Geiger, C.; Gomez-Escribano, J. P.; Greule, A.; Hadjithomas, M.; Haines, A. S.; Helfrich, E. J.; Hillwig, M. L.; Ishida, K.; Jones, A. C.; Jones, C. S.; Jungmann, K.; Kegler, C.; Kim, H. U.; Kötter, P.; Krug, D.; Masschelein, J.; Melnik, A. V.; Mantovani, S. M.; Monroe, E. A.; Moore, M.; Moss, N.; Nützmann, H. W.; Pan, G.; Pati, A.; Petras, D.; Reen, F. J.; Rosconi, F.; Rui, Z.; Tian, Z.; Tobias, N. J.; Tsunematsu, Y.; Wiemann, P.; Wyckoff, E.; Yan, X.; Yim, G.; Yu, F.; Xie, Y.; Aigle, B.; Apel, A. K.; Balibar, C. J.; Balskus, E. P.; Barona-Gómez, F.; Bechthold, A.; Bode, H. B.; Borriss, R.; Brady, S. F.; Brakhage, A. A.; Caffrey, P.; Cheng, Y. Q.; Clardy, J.; Cox, R. J.; De Mot, R.; Donadio, S.; Donia, M. S.; van der Donk, W. A.; Dorrestein, P. C.; Doyle, S.; Driessen, A. J.; Ehling-Schulz, M.; Entian, K. D.; Fischbach, M. A.; Gerwick, L.; Gerwick, W. H.; Gross, H.; Gust, B.; Hertweck, C.; Höfte, M.; Jensen, S. E.; Ju, J.; Katz, L.; Kaysser, L.; Klassen, J. L.; Keller, N. P.; Kormanec, J.; Kuipers, O. P.; Kuzuyama, T.; Kyrpides, N. C.; Kwon, H. J.; Lautru, S.; Lavigne, R.; Lee, C. Y.; Linquan, B.; Liu, X.; Liu, W.; Luzhetskyy, A.; Mahmud, T.; Mast, Y.; Méndez, C.; Metsä-Ketelä, M.; Micklefield, J.; Mitchell, D. A.; Moore, B. S.; Moreira, L. M.; Müller, R.; Neilan, B. A.; Nett, M.; Nielsen, J.; O’Gara, F.; Oikawa, H.; Osbourn, A.; Osburne, M. S.; Ostash, B.; Payne, S. M.; Pernodet, J. L.; Petricek, M.; Piel, J.; Ploux, O.; Raaijmakers, J. M.; Salas, J. A.; Schmitt, E. K.; Scott, B.; Seipke, R. F.; Shen, B.; Sherman, D. H.; Sivonen, K.; Smanski, M. J.; Sosio, M.; Stegmann, E.; Süssmuth, R. D.; Tahlan, K.; Thomas, C. M.; Tang, Y.; Truman, A. W.; Viaud, M.; Walton, J. D.; Walsh, C. T.; Weber, T.; van Wezel, G. P.; Wilkinson, B.; Willey, J. M.; Wohlleben, W.; Wright, G. D.; Ziemert, N.; Zhang, C.; Zotchev, S. B.; Breitling, R.; Takano, E.; Glöckner, F. O. Nat. Chem. Biol. 2015, 11, 625– 631,  DOI: 10.1038/nchembio.1890
    Google Scholar
    37
    Minimum information about a biosynthetic gene cluster
    Medema, Marnix H.; Kottmann, Renzo; Yilmaz, Pelin; Cummings, Matthew; Biggins, John B.; Blin, Kai; de Bruijn, Irene; Chooi, Yit Heng; Claesen, Jan; Coates, R. Cameron; Cruz-Morales, Pablo; Duddela, Srikanth; Duesterhus, Stephanie; Edwards, Daniel J.; Fewer, David P.; Garg, Neha; Geiger, Christoph; Gomez-Escribano, Juan Pablo; Greule, Anja; Hadjithomas, Michalis; Haines, Anthony S.; Helfrich, Eric J. N.; Hillwig, Matthew L.; Ishida, Keishi; Jones, Adam C.; Jones, Carla S.; Jungmann, Katrin; Kegler, Carsten; Kim, Hyun Uk; Koetter, Peter; Krug, Daniel; Masschelein, Joleen; Melnik, Alexey V.; Mantovani, Simone M.; Monroe, Emily A.; Moore, Marcus; Moss, Nathan; Nuetzmann, Hans-Wilhelm; Pan, Guohui; Pati, Amrita; Petras, Daniel; Reen, F. Jerry; Rosconi, Federico; Rui, Zhe; Tian, Zhenhua; Tobias, Nicholas J.; Tsunematsu, Yuta; Wiemann, Philipp; Wyckoff, Elizabeth; Yan, Xiaohui; Yim, Grace; Yu, Fengan; Xie, Yunchang; Aigle, Bertrand; Apel, Alexander K.; Balibar, Carl J.; Balskus, Emily P.; Barona-Gomez, Francisco; Bechthold, Andreas; Bode, Helge B.; Borriss, Rainer; Brady, Sean F.; Brakhage, Axel A.; Caffrey, Patrick; Cheng, Yi-Qiang; Clardy, Jon; Cox, Russell J.; De Mot, Rene; Donadio, Stefano; Donia, Mohamed S.; van der Donk, Wilfred A.; Dorrestein, Pieter C.; Doyle, Sean; Driessen, Arnold J. M.; Ehling-Schulz, Monika; Entian, Karl-Dieter; Fischbach, Michael A.; Gerwick, Lena; Gerwick, William H.; Gross, Harald; Gust, Bertolt; Hertweck, Christian; Hoefte, Monica; Jensen, Susan E.; Ju, Jianhua; Katz, Leonard; Kaysser, Leonard; Klassen, Jonathan L.; Keller, Nancy P.; Kormanec, Jan; Kuipers, Oscar P.; Kuzuyama, Tomohisa; Kyrpides, Nikos C.; Kwon, Hyung-Jin; Lautru, Sylvie; Lavigne, Rob; Lee, Chia Y.; Linquan, Bai; Liu, Xinyu; Liu, Wen; Luzhetskyy, Andriy; Mahmud, Taifo; Mast, Yvonne; Mendez, Carmen; Metsae-Ketelae, Mikko; Micklefield, Jason; Mitchell, Douglas A.; Moore, Bradley S.; Moreira, Leonilde M.; Mueller, Rolf; Neilan, Brett A.; Nett, Markus; Nielsen, Jens; O'Gara, Fergal; Oikawa, Hideaki; Osbourn, Anne; Osburne, Marcia S.; Ostash, Bohdan; Payne, Shelley M.; Pernodet, Jean-Luc; Petricek, Miroslav; Piel, Joern; Ploux, Olivier; Raaijmakers, Jos M.; Salas, Jose A.; Schmitt, Esther K.; Scott, Barry; Seipke, Ryan F.; Shen, Ben; Sherman, David H.; Sivonen, Kaarina; Smanski, Michael J.; Sosio, Margherita; Stegmann, Evi; Suessmuth, Roderich D.; Tahlan, Kapil; Thomas, Christopher M.; Tang, Yi; Truman, Andrew W.; Viaud, Muriel; Walton, Jonathan D.; Walsh, Christopher T.; Weber, Tilmann; van Wezel, Gilles P.; Wilkinson, Barrie; Willey, Joanne M.; Wohlleben, Wolfgang; Wright, Gerard D.; Ziemert, Nadine; Zhang, Changsheng; Zotchev, Sergey B.; Breitling, Rainer; Takano, Eriko; Gloeckner, Frank Oliver
    Nature Chemical Biology (2015), 11 (9), 625-631CODEN: NCBABT; ISSN:1552-4450. (Nature Publishing Group)
    A review and discussion. A wide variety of enzymic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Min. Information about a Biosynthetic Gene cluster (MIBiG) data std.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlKntrjN&md5=3ca6fcc3bfb657101131b18411d5a4c6
  38. 38
    Mazza, P.; Monciardini, P.; Cavaletti, L.; Sosio, M.; Donadio, S. Microb. Ecol. 2003, 45, 362– 72,  DOI: 10.1007/s00248-002-2038-4
    Google Scholar
    38
    Diversity of Actinoplanes and Related Genera Isolated from an Italian Soil
    Mazza, P.; Monciardini, P.; Cavaletti, L.; Sosio, M.; Donadio, S.
    Microbial Ecology (2003), 45 (4), 362-372CODEN: MCBEBU; ISSN:0095-3628. (Springer-Verlag New York Inc.)
    Actinoplanes and related genera are good producers of bioactive secondary metabolites. However, many strains within these genera present similar morphol. characteristics, and this prevents an effective discrimination of replicate strains during industrial isolation and screening programs. Using PCR-RFLP anal. of the 23S rDNA gene and of the 16S-23S intergenic spacer, we have analyzed 182 strains of Actinoplanes and related genera obtained through a selective isolation method from a single Italian soil. Combining the 23S and IGS data, 99 unique profiles were obsd., and morphol. undistinguishable strains were discriminated. Further analyses on a restricted no. of strains through 16S sequencing and hybridization to a probe for secondary metab. established a good correlation between strain diversity seen by PCR-RFLP and that seen by the other methods. Overall, the data indicate the presence of a high diversity of Actinoplanes and related genera isolated from a single Italian soil.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXksFWms78%253D&md5=a8f35f4ce647904e7be060e1b62081ae
  39. 39
    Weber, T.; Blin, K.; Duddela, S.; Krug, D.; Kim, H. U.; Bruccoleri, R.; Lee, S. Y.; Fischbach, M. A.; Müller, R.; Wohlleben, W.; Breitling, R.; Takano, E.; Medema, M. H. Nucleic Acids Res. 2015, 43, W237– 43,  DOI: 10.1093/nar/gkv437
    Google Scholar
    39
    antiSMASH 3.0-a comprehensive resource for the genome mining of biosynthetic gene clusters
    Weber, Tilmann; Blin, Kai; Duddela, Srikanth; Krug, Daniel; Kim, Hyun Uk; Bruccoleri, Robert; Lee, Sang Yup; Fischbach, Michael A.; Muller, Rolf; Wohlleben, Wolfgang; Breitling, Rainer; Takano, Eriko; Medema, Marnix H.
    Nucleic Acids Research (2015), 43 (W1), W237-W243CODEN: NARHAD; ISSN:0305-1048. (Oxford University Press)
    Microbial secondary metab. constitutes a rich source of antibiotics, chemotherapeutics, insecticides and other high-value chems. Genome mining of gene clusters that encode the biosynthetic pathways for these metabolites has become a key methodol. for novel compd. discovery. In 2011, we introduced antiSMASH, a web server and stand-alone tool for the automatic genomic identification and anal. of biosynthetic gene clusters, available at http://antismash.secondarymetabolites.org. Here, we present version 3.0 of antiSMASH, which has undergone major improvements. A full integration of the recently published ClusterFinder algorithm now allows using this probabilistic algorithm to detect putative gene clusters of unknown types. Also, a new dereplication variant of the ClusterBlast module now identifies similarities of identified clusters to any of 1172 clusters with known end products. At the enzyme level, active sites of key biosynthetic enzymes are now pinpointed through a curated pattern-matching procedure and Enzyme Commission nos. are assigned to functionally classify all enzyme-coding genes. Addnl., chem. structure prediction has been improved by incorporating polyketide redn. states. Finally, in order for users to be able to organize and analyze multiple antiSMASH outputs in a private setting, a new XML output module allows offline editing of antiSMASH annotations within the Geneious software.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVymtbzN&md5=03415650d89df1a3a1c812be313af9a1

Cited By

ARTICLE SECTIONS
Jump To

This article is cited by 7 publications.

  1. Jason B. Hedges, Katherine S. Ryan. Biosynthetic Pathways to Nonproteinogenic α-Amino Acids. Chemical Reviews 2020, 120 (6) , 3161-3209. https://doi.org/10.1021/acs.chemrev.9b00408
  2. Weizhuo Tang, Die Zhang, Jing Xu, Shuping Wang, Bin Wei, Lei Li. Spongisulfins A-C, three S-bridged angucycline dimers from Spongiactinospora rosea LHW63015 and their gut epithelium protective activity in Drosophila melanogaster. Arabian Journal of Chemistry 2024, 17 (4) , 105687. https://doi.org/10.1016/j.arabjc.2024.105687
  3. Max A. J. Rivers, Andrew N. Lowell. Expanding the Biosynthetic Toolbox: The Potential and Challenges of In Vitro Type II Polyketide Synthase Research. SynBio 2024, 2 (1) , 85-111. https://doi.org/10.3390/synbio2010006
  4. Marianna Iorio, Andrea Gentile, Cristina Brunati, Arianna Tocchetti, Paolo Landini, Sonia Ilaria Maffioli, Stefano Donadio, Margherita Sosio. Allopeptimicins: unique antibacterial metabolites generated by hybrid PKS-NRPS, with original self-defense mechanism in Actinoallomurus. RSC Advances 2022, 12 (26) , 16640-16655. https://doi.org/10.1039/D2RA02094G
  5. Jia Wang, Ruihua Zhang, Xin Chen, Xinxiao Sun, Yajun Yan, Xiaolin Shen, Qipeng Yuan. Biosynthesis of aromatic polyketides in microorganisms using type II polyketide synthases. Microbial Cell Factories 2020, 19 (1) https://doi.org/10.1186/s12934-020-01367-4
  6. Jiangkun Dai, Rui Han, Yujie Xu, Na Li, Junru Wang, Wenjia Dan. Recent progress of antibacterial natural products: Future antibiotics candidates. Bioorganic Chemistry 2020, 101 , 103922. https://doi.org/10.1016/j.bioorg.2020.103922
  7. 治情 邹. Comparison of Four Methods for Extracting the Genomic DNA of Staphylococcus aureus. Hans Journal of Biomedicine 2019, 09 (04) , 154-161. https://doi.org/10.12677/HJBM.2019.94023
Download PDF

  • Abstract

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 1

    Figure 1. HPLC trace of an ethanol extract from strain ID40491 (see text for details).

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 2

    Figure 2. Structures of compounds and NMR correlations. (a) Structures of 1 and 2. (b) Main 1H–1H COSY, NOESY, and 1H–15N HMBC correlations. (c) Observed HMBC and 13C–13C COSY correlations of 1.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 3

    Figure 3. Oxidative cleavage of 1.

    High Resolution Image
    Download MS PowerPoint Slide

    Figure 4

    Figure 4. Organization of the enduracyclinone biosynthetic genes. The deduced functions are color-coded as indicated and summarized in Table 2. end, enduracididine; mCoA, malonyl-CoA.

    High Resolution Image
    Download MS PowerPoint Slide

  • References

    ARTICLE SECTIONS
    Jump To

    This article references 39 other publications.

    1. 1
      Moloney, M. G. Trends Pharmacol. Sci. 2016, 37, 689– 701,  DOI: 10.1016/j.tips.2016.05.001
      1
      Natural Products as a Source for Novel Antibiotics
      Moloney, Mark G.
      Trends in Pharmacological Sciences (2016), 37 (8), 689-701CODEN: TPHSDY; ISSN:0165-6147. (Elsevier Ltd.)
      A review. Natural products have historically been of crucial importance in the identification and development of antibacterial agents. Interest in these systems has waned in recent years, but the rapid emergence of resistant bacterial strains has forced their re-evaluation as a route to identify novel chem. skeletons with antibacterial activity for elaboration in drug development. This overview examines the current situation, highlights new natural product systems which have been found, together with re-examn. of some old ones, and new technologies for their identification. While natural products certainly have the potential to re-emerge as a key start-point in antibacterial drug discovery, reports of new or reinvestigated structures need to be supported with sufficient quality chem. (soly., stability), biochem. (including toxicity in particular, along with target information) and microbiol. [min. inhibitory concn. (MIC) and resistance frequency] validation data to assist in the identification of promising hit structures and to avoid wasted effort from trawling over already cultivated territory. This is particularly important in a resource-limited research environment.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XotF2rtrw%253D&md5=091645e56653a4d8d8d43eccad532c00
    2. 2
      Brown, E. D.; Wright, G. D. Nature 2016, 529, 336– 343,  DOI: 10.1038/nature17042
      2
      Antibacterial drug discovery in the resistance era
      Brown, Eric D.; Wright, Gerard D.
      Nature (London, United Kingdom) (2016), 529 (7586), 336-343CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      A review. The looming antibiotic resistance crisis has penetrated the consciousness of clinicians, researchers, policymakers, politicians and the public at large. The evolution and widespread distribution of antibiotic resistance elements in bacterial pathogens has made diseases that were once easily treatable deadly again. Unfortunately, accompanying the rise in global resistance is a failure in antibacterial drug discovery. Lessons from the history of antibiotic discovery and fresh understanding of antibiotic action and the cell biol. of microorganisms have the potential to deliver twenty-first century medicines that are able to control infection in the resistance era.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht1Oisro%253D&md5=62e0454601a242db039e60d77be26406
    3. 3
      Bumann, D. Curr. Opin. Microbiol. 2008, 11, 387– 392,  DOI: 10.1016/j.mib.2008.08.002
      3
      Has nature already identified all useful antibacterial targets?
      Bumann, Dirk
      Current Opinion in Microbiology (2008), 11 (5), 387-392CODEN: COMIF7; ISSN:1369-5274. (Elsevier B.V.)
      A review. Novel antimicrobial targets are urgently needed to overcome rising antibiotic resistance of important human pathogens. However, evidence from previous antimicrobial screenings, in silico anal., and exptl. target evaluation suggests that the no. of novel bacterial broad-spectrum targets might be severely limited. This is because of the poor conservation of genes among diverse bacterial pathogens, partial functional redundancy and nutrient-rich host environments. Remaining opportunities under these circumstances include the development of narrow-spectrum antibiotics against specific pathogens and the exploration of target combinations.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlGgsL%252FL&md5=1a188819439c63fc02e061163c8d718b
    4. 4
      Demain, A. L. J. Ind. Microbiol. Biotechnol. 2014, 41, 185– 201,  DOI: 10.1007/s10295-013-1325-z
      4
      Importance of microbial natural products and the need to revitalize their discovery
      Demain, Arnold L.
      Journal of Industrial Microbiology & Biotechnology (2014), 41 (2), 185-201CODEN: JIMBFL; ISSN:1367-5435. (Springer)
      A review. Microbes are the leading producers of useful natural products. Natural products from microbes and plants make excellent drugs. Significant portions of the microbial genomes are devoted to prodn. of these useful secondary metabolites. A single microbe can make a no. of secondary metabolites, as high as 50 compds. The most useful products include antibiotics, anticancer agents, immunosuppressants, but products for many other applications, e.g., antivirals, anthelmintics, enzyme inhibitors, nutraceuticals, polymers, surfactants, bioherbicides, and vaccines were commercialized. Unfortunately, due to the decrease in natural product discovery efforts, drug discovery has decreased in the past 20 years. The reasons include excessive costs for clin. trials, too short a window before the products become generics, difficulty in discovery of antibiotics against resistant organisms, and short treatment times by patients for products such as antibiotics. Despite these difficulties, technol. to discover new drugs has advanced, e.g., combinatorial chem. of natural product scaffolds, discoveries in biodiversity, genome mining, and systems biol. Of great help would be government extension of the time before products become generic.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtl2qtrrI&md5=657e82af420b3e01942df70b6f691c59
    5. 5
      Newman, D. J.; Cragg, G. M. J. Nat. Prod. 2012, 75, 311– 335,  DOI: 10.1021/np200906s
      5
      Natural Products As Sources of New Drugs over the 30 Years from 1981 to 2010
      Newman, David J.; Cragg, Gordon M.
      Journal of Natural Products (2012), 75 (3), 311-335CODEN: JNPRDF; ISSN:0163-3864. (American Chemical Society-American Society of Pharmacognosy)
      This review is an updated and expanded version of the three prior reviews that were published in this journal in 1997, 2003, and 2007. In the case of all approved therapeutic agents, the time frame has been extended to cover the 30 years from Jan. 1, 1981, to Dec. 31, 2010, for all diseases worldwide, and from 1950 (earliest so far identified) to Dec. 2010 for all approved antitumor drugs worldwide. We have continued to utilize our secondary subdivision of a "natural product mimic" or "NM" to join the original primary divisions and have added a new designation, "natural product botanical" or "NB", to cover those botanical "defined mixts." that have now been recognized as drug entities by the FDA and similar organizations. From the data presented, the utility of natural products as sources of novel structures, but not necessarily the final drug entity, is still alive and well. Thus, in the area of cancer, over the time frame from around the 1940s to date, of the 175 small mols., 131, or 74.8%, are other than "S" (synthetic), with 85, or 48.6%, actually being either natural products or directly derived therefrom. In other areas, the influence of natural product structures is quite marked, with, as expected from prior information, the anti-infective area being dependent on natural products and their structures. Although combinatorial chem. techniques have succeeded as methods of optimizing structures and have been used very successfully in the optimization of many recently approved agents, we are able to identify only one de novo combinatorial compd. approved as a drug in this 30-yr time frame. We wish to draw the attention of readers to the rapidly evolving recognition that a significant no. of natural product drugs/leads are actually produced by microbes and/or microbial interactions with the "host from whence it was isolated", and therefore we consider that this area of natural product research should be expanded significantly.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XitVeku78%253D&md5=395ac7378f07d122a5789d7b440f858d
    6. 6
      Ling, L. L.; Schneider, T.; Peoples, A. J.; Spoering, A. L.; Engels, I.; Conlon, B. P.; Mueller, A.; Schaberle, T. F.; Hughes, D. E.; Epstein, S.; Jones, M.; Lazarides, L.; Steadman, V. A.; Cohen, D. R.; Felix, C. R.; Fetterman, K. A.; Millet, W. P.; Nitti, A. G.; Zullo, A. M.; Chen, C.; Lewis, K. Nature 2015, 517, 455– 459,  DOI: 10.1038/nature14098
      6
      A new antibiotic kills pathogens without detectable resistance
      Ling, Losee L.; Schneider, Tanja; Peoples, Aaron J.; Spoering, Amy L.; Engels, Ina; Conlon, Brian P.; Mueller, Anna; Schaberle, Till F.; Hughes, Dallas E.; Epstein, Slava; Jones, Michael; Lazarides, Linos; Steadman, Victoria A.; Cohen, Douglas R.; Felix, Cintia R.; Fetterman, K. Ashley; Millett, William P.; Nitti, Anthony G.; Zullo, Ashley M.; Chen, Chao; Lewis, Kim
      Nature (London, United Kingdom) (2015), 517 (7535), 455-459CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      Antibiotic resistance is spreading faster than the introduction of new compds. into clin. practice, causing a public health crisis. Most antibiotics were produced by screening soil microorganisms, but this limited resource of cultivable bacteria was overmined by the 1960s. Synthetic approaches to produce antibiotics have been unable to replace this platform. Uncultured bacteria make up approx. 99% of all species in external environments, and are an untapped source of new antibiotics. We developed several methods to grow uncultured organisms by cultivation in situ or by using specific growth factors. Here we report a new antibiotic that we term teixobactin, discovered in a screen of uncultured bacteria. Teixobactin inhibits cell wall synthesis by binding to a highly conserved motif of lipid II (precursor of peptidoglycan) and lipid III (precursor of cell wall teichoic acid). We did not obtain any mutants of Staphylococcus aureus or Mycobacterium tuberculosis resistant to teixobactin. The properties of this compd. suggest a path towards developing antibiotics that are likely to avoid development of resistance.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFOju7w%253D&md5=27e302d7d44a549a91aa52113c3b4ad8
    7. 7
      Maffioli, S. I.; Zhang, Y.; Degen, D.; Carzaniga, T.; Del Gatto, G.; Serina, S.; Monciardini, P.; Mazzetti, C.; Guglierame, P.; Candiani, G.; Chiriac, A. I.; Facchetti, G.; Kaltofen, P.; Sahl, H. G.; Dehò, G.; Donadio, S.; Ebright, R. H. Cell 2017, 169, 1240– 1248e1223,  DOI: 10.1016/j.cell.2017.05.042
      7
      Antibacterial Nucleoside-Analog Inhibitor of Bacterial RNA Polymerase
      Maffioli, Sonia I.; Zhang, Yu; Degen, David; Carzaniga, Thomas; Del Gatto, Giancarlo; Serina, Stefania; Monciardini, Paolo; Mazzetti, Carlo; Guglierame, Paola; Candiani, Gianpaolo; Chiriac, Alina Iulia; Facchetti, Giuseppe; Kaltofen, Petra; Sahl, Hans-Georg; Deho, Gianni; Donadio, Stefano; Ebright, Richard H.
      Cell (Cambridge, MA, United States) (2017), 169 (7), 1240-1248.e23CODEN: CELLB5; ISSN:0092-8674. (Cell Press)
      Drug-resistant bacterial pathogens pose an urgent public-health crisis. Here, we report the discovery, from microbial-ext. screening, of a nucleoside-analog inhibitor that inhibits bacterial RNA polymerase (RNAP) and exhibits antibacterial activity against drug-resistant bacterial pathogens: pseudouridimycin (PUM). PUM is a natural product comprising a formamidinylated, N-hydroxylated Gly-Gln dipeptide conjugated to 6'-amino-pseudouridine. PUM potently and selectively inhibits bacterial RNAP in vitro, inhibits bacterial growth in culture, and clears infection in a mouse model of Streptococcus pyogenes peritonitis. PUM inhibits RNAP through a binding site on RNAP (the NTP addn. site) and mechanism (competition with UTP for occupancy of the NTP addn. site) that differ from those of the RNAP inhibitor and current antibacterial drug rifampin (Rif). PUM exhibits additive antibacterial activity when co-administered with Rif, exhibits no cross-resistance with Rif, and exhibits a spontaneous resistance rate an order-of-magnitude lower than that of Rif. PUM is a highly promising lead for antibacterial therapy.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVWrtrnI&md5=037230d61bb316927bda72308a7a7656
    8. 8
      Monciardini, P.; Iorio, M.; Maffioli, S.; Sosio, M.; Donadio, S. Microb. Biotechnol. 2014, 7, 209– 220,  DOI: 10.1111/1751-7915.12123
      8
      Discovering new bioactive molecules from microbial sources
      Monciardini, Paolo; Iorio, Marianna; Maffioli, Sonia; Sosio, Margherita; Donadio, Stefano
      Microbial Biotechnology (2014), 7 (3), 209-220CODEN: MBIIB2; ISSN:1751-7915. (Wiley-Blackwell)
      A review. Summary : There is an increased need for new drug leads to treat diseases in humans, animals and plants. A dramatic example is represented by the need for novel and more effective antibiotics to combat multidrug-resistant microbial pathogens. Natural products represent a major source of approved drugs and still play an important role in supplying chem. diversity, despite a decreased interest by large pharmaceutical companies. Novel approaches must be implemented to decrease the chances of rediscovering the tens of thousands of known natural products. In this review, we present an overview of natural product screening, focusing particularly on microbial products. Different approaches can be implemented to increase the probability of finding new bioactive mols. We thus present the rationale and selected examples of the use of hypersensitive assays; of accessing unexplored microorganisms, including the metagenome; and of genome mining. We then focus our attention on the technol. platform that we are currently using, consisting of approx. 70 000 microbial strains, mostly actinomycetes and filamentous fungi, and discuss about high-quality screening in the search for bioactive mols. Finally, two case studies are discussed, including the spark that arose interest in the compd.: in the case of orthoformimycin, the novel mechanism of action predicted a novel structural class; in the case of NAI-112, structural similarity pointed out to a possible in vivo activity. Both predictions were then exptl. confirmed.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmtVCjs7Y%253D&md5=35e0a536376282ad4bc3b34f26f2a094
    9. 9
      Jabes, D.; Donadio, S. Methods Mol. Biol. 2010, 618, 31– 45,  DOI: 10.1007/978-1-60761-594-1_3
      9
      Strategies for the isolation and characterization of antibacterial lantibiotics
      Jabes, Daniela; Donadio, Stefano
      Methods in Molecular Biology (Totowa, NJ, United States) (2010), 618 (Antimicrobial Peptides), 31-45CODEN: MMBIED; ISSN:1064-3745. (Humana Press Inc.)
      Lantibiotics are biol. active peptides produced by several strains from the phyla Firmicutes and Actinobacteria. They are ribosomally synthesized and undergo posttranslational modifications that endow them with the characteristic (methyl)-lanthionine residues. As a result, lantibiotics contain a variable no. of rings, each carrying one thioether link. Many lantibiotics inhibit growth of Gram-pos. bacterial strains by interfering with peptidoglycan formation. Because they bind to the key intermediate lipid II at a site not affected by clin. used antibiotics, they are effective against multidrug-resistant strains. We describe a bioassay-based method suitable for finding antibacterial lantibiotics from actinomycete strains and provide selected procedures for characterizing newly discovered lantibiotics for their antibacterial properties.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtVSlu73F&md5=44d90108cf44a26d7dc10d41f0bc057f
    10. 10
      Simone, M.; Monciardini, P.; Gaspari, E.; Donadio, S.; Maffioli, S. I. J. Antibiot. 2013, 66, 73– 78,  DOI: 10.1038/ja.2012.92
      There is no corresponding record for this reference.
    11. 11
      Maffioli, S. I.; Monciardini, P.; Catacchio, B.; Mazzetti, C.; Münch, D.; Brunati, C.; Sahl, H. G.; Donadio, S. ACS Chem. Biol. 2015, 10, 1034– 1042,  DOI: 10.1021/cb500878h
      There is no corresponding record for this reference.
    12. 12
      Iorio, M.; Sasso, O.; Maffioli, S. I.; Bertorelli, R.; Monciardini, P.; Sosio, M.; Bonezzi, F.; Summa, M.; Brunati, C.; Bordoni, R.; Corti, G.; Tarozzo, G.; Piomelli, D.; Reggiani, A.; Donadio, S. ACS Chem. Biol. 2014, 9, 398– 404,  DOI: 10.1021/cb400692w
      There is no corresponding record for this reference.
    13. 13
      De Pascale, G.; Grigoriadou, C.; Losi, D.; Ciciliato, I.; Sosio, M.; Donadio, S. J. Appl. Microbiol. 2007, 103, 133– 140,  DOI: 10.1111/j.1365-2672.2006.03231.x
      13
      Validation for high-throughput screening of a VanRS-based reporter gene assay for bacterial cell wall inhibitors
      De Pascale, G.; Grigoriadou, C.; Losi, D.; Ciciliato, I.; Sosio, M.; Donadio, S.
      Journal of Applied Microbiology (2007), 103 (1), 133-140CODEN: JAMIFK; ISSN:1364-5072. (Blackwell Publishing Ltd.)
      The present study was undertaken to validate, for antibiotic discovery, a reporter gene assay based on a Bacillus subtilis strain expressing the Enterococcus faecium vanRS genes and a vanH-lacZ fusion, which produced β-galactosidase activity in the presence of cell wall inhibitors (CWI) and lysozyme. The reporter assay was miniaturized, automated and validated with antibiotics and tested against portions of chem. and microbial ext. libraries. The assay is simple, fast and reproducible and can detect all CWI, sometimes at concns. lower than those necessary to inhibit bacterial growth. However, some membrane-interfering compds. also generate comparable signals. While most CWI elicit a signal that is transcription-dependent and abolished in an osmoprotective medium, transcription is not required for β-galactosidase activity brought about by the membrane-interfering compds. At least two distinct mechanisms appear to lead to enzymic activity in the reporter strain. Effective counterscreens can be designed to discard the undesired classes of compds. Extensive validation is required before introducing a reporter assay in high-throughput screening. However, the ease of operation and manipulation makes the reporter assays powerful tools for antibiotic discovery.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXovVOqtr8%253D&md5=b0619f682170c6255477763190b62a69
    14. 14
      Gerber, N. N.; Lechevalier, M. P. Can. J. Chem. 1984, 62, 2818– 2821,  DOI: 10.1139/v84-477
      There is no corresponding record for this reference.
    15. 15
      Rickards, R. W. J. Antibiot. 1989, 42, 336– 339,  DOI: 10.7164/antibiotics.42.336
      There is no corresponding record for this reference.
    16. 16
      Ogawa, H.; Natori, S. Chem. Pharm. Bull. 1968, 16, 1709– 1720,  DOI: 10.1248/cpb.16.1709
      There is no corresponding record for this reference.
    17. 17
      Cameron, D. W.; Cromartie, R. I. T.; Kingston, D. G. I.; Todd, L. J. Chem. Soc. 1964, 0, 51– 61,  DOI: 10.1039/JR9640000051
      17
      Coloring matters of the aphididae. XVII. The structure and absolute stereochemistry of the protoaphins
      Cameron, D. W.; Cromartie, R. I. T.; Kingston, D. G. I.; Todd, Lord
      Journal of the Chemical Society (1964), (Jan.), 51-61CODEN: JCSOA9; ISSN:0368-1769.
      Structures (I) and (II) (Gl = glucose moiety) are proposed for protoaphins-fb and -sl, resp. On mild redn., a process involving fission of an activated 1,1'-binaphthyl system, each aphin yields a mixt. of a 5,7-dihydroxy-1,4-naphthoquinone and the glucoside of a 1,3,8-naphthalenetriol. The quinone A obtained from the -fb isomer differs from that (A') of the -sl isomer, but the same glucoside B, which can be converted into quinone A, is obtained from each. Oxidn. of quinones A and A' yields the same DD(+)-dilactic acid and this dets. both structure and abs. configuration of the nonaromatic portions of the mols. The two protoaphins differ from one another in the configuration at one center of asymmetry only.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaF2cXjvVOgsA%253D%253D&md5=141bae63f88c85a12afb37124b689777
    18. 18
      He, H.; Yang, H. Y.; Luckman, S. W.; Bernan, V. S.; Tsai, G.; Roll, D. M.; Carter, G. T. Helv. Chim. Acta 2004, 87, 1385– 1391,  DOI: 10.1002/hlca.200490126
      There is no corresponding record for this reference.
    19. 19
      Banskota, A. H.; Aouidate, M.; Sørensen, D.; Ibrahim, A.; Piraee, M.; Zazopoulos, E.; Alarco, A. M.; Gourdeau, H.; Mellon, C.; Farnet, C. M.; Falardeau, P.; McAlpine, J. B. J. Antibiot. 2009, 62, 565– 570,  DOI: 10.1038/ja.2009.77
      There is no corresponding record for this reference.
    20. 20
      Winter, D. K.; Sloman, D. L.; Porco, J. A. Nat. Prod. Rep. 2013, 30, 382– 391,  DOI: 10.1039/c3np20122h
      20
      Polycyclic xanthone natural products: structure, biological activity and chemical synthesis
      Winter, Dana K.; Sloman, David L.; Porco, John A, Jr.
      Natural Product Reports (2013), 30 (3), 382-391CODEN: NPRRDF; ISSN:0265-0568. (Royal Society of Chemistry)
      A review. Polycyclic xanthone natural products are a family of polyketides which are characterized by highly oxygenated, angular hexacyclic frameworks. In the last decade, this novel class of mols. has attracted noticeable attention from the synthetic and biol. communities due to emerging reports of their potential use as antitumor agents. The aim of this article is to highlight the most recent developments of this subset of the xanthone family by detailing the innate challenges of the construction of this class of natural products, new synthetic approaches, and pharmacol. data.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXisVKqu70%253D&md5=2bd2518979ea526bef54a38d3c4061fe
    21. 21
      Aoyama, T.; Kojima, F.; Abe, F.; Muraoka, Y.; Naganawa, H.; Takeuchi, T.; Aoyagi, T. J. Antibiot. 1993, 46, 914– 920,  DOI: 10.7164/antibiotics.46.914
      21
      Bequinostatins A and B, new inhibitors of glutathione S-transferase, produced by Streptomyces sp. MI384-DF12: production, isolation, structure determination and biological activities
      Aoyama, Takayuki; Kojima, Fukiko; Abe, Fuminori; Muraoka, Yasuhiko; Naganawa, Hiroshi; Takeuchi, Tomio; Aoyagi, Takaaki
      Journal of Antibiotics (1993), 46 (6), 914-20CODEN: JANTAJ; ISSN:0021-8820.
      New benzo[a]naphthacenequinone metabolites, designated bequinostatins A and B (I and II), were isolated from the culture broth of the benastatin-producing strain Streptomyces sp. MI384-DF12. The structures of bequinostatins A and B were detd. by spectral analyses to be 5,6,8,13-tetrahydro-1,6,7,9,11-pentahydroxy-8,13-dioxo-3-pentylbenzo[a]naphthacene-2-carboxylic acid and 2-decarboxybequinostatin A, resp. Bequinostatin A showed considerable inhibitory activity against human pi class glutathione S-transferase.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXhtVWgsL8%253D&md5=4e67c9eb2bc60e316c620fbeb5f6c53f
    22. 22
      Atkinson, D. J.; Naysmith, B. J.; Furkert, D. P.; Brimble, M. A. Beilstein J. Org. Chem. 2016, 12, 2325– 2342,  DOI: 10.3762/bjoc.12.226
      22
      Enduracididine, a rare amino acid component of peptide antibiotics: Natural products and synthesis
      Atkinson, Darcy J.; Naysmith, Briar J.; Furkert, Daniel P.; Brimble, Margaret A.
      Beilstein Journal of Organic Chemistry (2016), 12 (), 2325-2342CODEN: BJOCBH; ISSN:1860-5397. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)
      A review. Rising resistance to current clin. antibacterial agents is an imminent threat to global public health and highlights the demand for new lead compds. for drug discovery. One such potential lead compd., the peptide antibiotic teixobactin, was recently isolated from an uncultured bacterial source, and demonstrates remarkably high potency against a wide range of resistant pathogens without apparent development of resistance. A rare amino acid residue component of teixobactin, enduracididine, is only known to occur in a small no. of natural products that also possess promising antibiotic activity. This review highlights the presence of enduracididine in natural products, its biosynthesis together with a review of analogs of enduracididine. Reported synthetic approaches to the cyclic guanidine structure of enduracididine are discussed, illustrating the challenges encountered to date in the development of efficient synthetic routes to facilitate drug discovery efforts inspired by the discovery of teixobactin.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsVyjsbo%253D&md5=64fd7a0bab40306e979fc4ffae919138
    23. 23
      Yin, X.; Zabriskie, T. M. Microbiology 2006, 152, 2969– 2983,  DOI: 10.1099/mic.0.29043-0
      There is no corresponding record for this reference.
    24. 24
      Han, L.; Schwabacher, A. W.; Moran, G. R.; Silvaggi, N. R. Biochemistry 2015, 54, 7029– 7040,  DOI: 10.1021/acs.biochem.5b01016
      24
      Streptomyces wadayamensis MppP Is a Pyridoxal 5'-Phosphate-Dependent L-Arginine α-Deaminase, γ-Hydroxylase in the Enduracididine Biosynthetic Pathway
      Han, Lanlan; Schwabacher, Alan W.; Moran, Graham R.; Silvaggi, Nicholas R.
      Biochemistry (2015), 54 (47), 7029-7040CODEN: BICHAW; ISSN:0006-2960. (American Chemical Society)
      L-Enduracididine (L-End) is a nonproteinogenic amino acid found in a no. of bioactive peptides, including the antibiotics teixobactin, enduracidin, and mannopeptimycin. The potent activity of these compds. against antibiotic-resistant pathogens like MRSA and their novel mode of action have garnered considerable interest for the development of these peptides into clin. relevant antibiotics. This goal has been hampered, at least in part, by the fact that L-End is difficult to synthesize and not currently com. available. We have begun to elucidate the biosynthetic pathway of this unusual building block. In mannopeptimycin-producing strains, like Streptomyces wadayamensis, L-End is produced from L-Arg by the action of three enzymes: MppP, MppQ, and MppR. Herein, we report the structural and functional characterization of MppP. This pyridoxal 5'-phosphate (PLP)-dependent enzyme was predicted to be a fold type I aminotransferase on the basis of sequence anal. We show that MppP is actually the first example of a PLP-dependent hydroxylase that catalyzes a reaction of L-Arg with dioxygen to yield a mixt. of 2-oxo-4-hydroxy-5-guanidinovaleric acid and 2-oxo-5-guanidinovaleric acid in a 1.7:1 ratio. The structure of MppP with PLP bound to the catalytic lysine residue (Lys221) shows that, while the tertiary structure is very similar to those of the well-studied aminotransferases, there are differences in the arrangement of active site residues around the cofactor that likely account for the unusual activity of this enzyme. The structure of MppP with the substrate analog D-Arg bound shows how the enzyme binds its substrate and indicates why D-Arg is not a substrate. On the basis of this work and previous work with MppR, we propose a plausible biosynthetic scheme for L-End.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslykur7M&md5=9ea1af83bf7f5dc68866544056b62c23
    25. 25
      Magarvey, N. A.; Haltli, B.; He, M.; Greenstein, M.; Hucul, J. A. Antimicrob. Agents Chemother. 2006, 50, 2167– 2177,  DOI: 10.1128/AAC.01545-05
      25
      Biosynthetic pathway for mannopeptimycins, lipoglycopeptide antibiotics active against drug-resistant Gram-positive pathogens
      Magarvey, Nathan A.; Haltli, Brad; He, Min; Greenstein, Michael; Hucul, John A.
      Antimicrobial Agents and Chemotherapy (2006), 50 (6), 2167-2177CODEN: AMACCQ; ISSN:0066-4804. (American Society for Microbiology)
      The mannopeptimycins are a novel class of lipoglycopeptide antibiotics active against multidrug-resistant pathogens with potential as clin. useful antibacterials. This report is the first to describe the biosynthesis of this novel class of mannosylated lipoglycopeptides. Included here are the cloning, sequencing, annotation, and manipulation of the mannopeptimycin biosynthetic gene cluster from Streptomyces hygroscopicus NRRL 30439. Encoded by genes within the mannopeptimycin biosynthetic gene cluster are enzymes responsible for the generation of the hexapeptide core (nonribosomal peptide synthetases [NRPS]) and tailoring reactions (mannosylation, isovalerylation, hydroxylation, and methylation). The NRPS system is noncanonical in that it has six modules utilizing only five amino acid-specific adenylation domains and it lacks a prototypical NRPS macrocyclizing thioesterase domain. Anal. of the mannopeptimycin gene cluster and its engineering has elucidated the mannopeptimycin biosynthetic pathway and provides the framework to make new and improved mannopeptimycins biosynthetically.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XlsVOiurc%253D&md5=fea95a0f18946cb30891bc9b38361d58
    26. 26
      Zhan, J.; Qiao, K.; Tang, Y. ChemBioChem 2009, 10, 1447– 1452,  DOI: 10.1002/cbic.200900082
      There is no corresponding record for this reference.
    27. 27
      Iorio, M.; Cruz, J.; Simone, M.; Bernasconi, A.; Brunati, C.; Sosio, M.; Donadio, S.; Maffioli, S. I. J. Nat. Prod. 2017, 80, 819– 827,  DOI: 10.1021/acs.jnatprod.6b00654
      27
      Antibacterial Paramagnetic Quinones from Actinoallomurus
      Iorio, Marianna; Cruz, Joao; Simone, Matteo; Bernasconi, Alice; Brunati, Cristina; Sosio, Margherita; Donadio, Stefano; Maffioli, Sonia I.
      Journal of Natural Products (2017), 80 (4), 819-827CODEN: JNPRDF; ISSN:0163-3864. (American Chemical Society-American Society of Pharmacognosy)
      Four metabolites, designated paramagnetoquinone A (I, R1=OMe, R2=NHCH3), B (I, R1=R2=OMe), C, and D, were isolated from 3 strains belonging to the actinomycete genus Actinoallomurus. A and B showed potent antibacterial activity with MIC values <0.015 μg/mL against Gram-pos. pathogens, including antibiotic-resistant strains. Since compds. A and B were NMR-silent due to the presence of an oxygen radical, structure elucidation was achieved through a combination of derivatizations, oxidns., and anal. of 13C-labeled compds. The paramagnetoquinones share the same carbon scaffold as tetracenomycin but carry 2 quinones and a 5-membered lactone fused to the arom. system. B and A are identical except for an unprecedented replacement of a methoxy in B by a methylamino group in A. Related compds. devoid of Me group(s) and of antibacterial activity were isolated from a different Actinoallomurus strain. The likely pmq biosynthetic gene cluster was identified from strain ID145113. While the cluster encodes many of the expected enzymes involved in the formation of arom. polyketides, it also encodes a dedicated ketoacid dehydrogenase complex and an unusual acyl carrier protein transacylase, suggesting that an unusual starter unit might prime the polyketide synthase.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXjtVajtLc%253D&md5=80abbea165639e21cc136aa1e1f431da
    28. 28
      Drautz, H.; Keller-Schierlein, W.; Zähner, H. Arch. Microbiol. 1975, 106, 175– 190,  DOI: 10.1007/BF00446521
      28
      Metabolic products of microorganisms. 149. Lysolipin I, a new antibiotic from Streptomyces violaceoniger
      Drautz, H.; Keller-Schierlein, W.; Zaehner, H.
      Archives of Microbiology (1975), 106 (3), 175-90CODEN: AMICCW; ISSN:0302-8933.
      From the cultures of S. violaceoniger, strain Tue 96, 2 new lipophilic antibiotics, lysolipin I [59113-57-4] and lysolipid X [59029-83-3] were isolated. The latter one is chem. unstable and is easily transformed to lysolipin I. The deeply yellow lysolipin I has a mol. formula C29H24ClNO11. It was characterized by the ir, uv, H-NMR and 13C-NMR spectra, which make a quinone structure very probable. Lysolipin I is active against gram-pos. and gram-neg. bacteria. However, enterobacteria are only inhibited in high diln., when the membrane permeation is damaged. Lysolipin I acts lytically against bacterial cells. Its activity is decreased by several lipids. The site of action is the biosynthesis of bacterial cell walls, an interaction with the carrier lipid for murein intermediates being probable.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE28Xhslyit7k%253D&md5=1243d24899e44bdde079a6cff15a2bcc
    29. 29
      Nakagawa, A.; Iwai, Y.; Shimizu, H.; Omura, S. J. Antibiot. 1986, 39, 1636– 1638,  DOI: 10.7164/antibiotics.39.1636
      There is no corresponding record for this reference.
    30. 30
      Kobayashi, K.; Nishino, C.; Ohya, J.; Sato, S.; Mikawa, T.; Shiobara, Y.; Kodama, M. J. Antibiot. 1988, 41, 741– 750,  DOI: 10.7164/antibiotics.41.741
      30
      Actinoplanones C, D, E, F and G, new cytotoxic polycyclic xanthones from Actinoplanes sp
      Kobayashi, Koji; Nishino, Chikao; Ohya, Junichi; Sato, Shigeru; Mikawa, Takashi; Shiobara, Yoshinori; Kodama, Mitsuaki
      Journal of Antibiotics (1988), 41 (6), 741-50CODEN: JANTAJ; ISSN:0021-8820.
      Five new cytotoxic polycyclic xanthones were isolated from the culture broth of Actinoplanes sp. R-304 and were named actinoplanones C, D, E, F, and G. Actinoplanones C and G showed very strong cytotoxicity against HeLa cells at <0.00004 μg/mL dosage (IC50). The structures were varieties of actinoplanone A (I) for the N-2 and C-4 substituents. All or several actinoplanones showed strong antimicrobial activities against bacteria and the rice blast fungus. When tested for cytotoxicity against various tumor cells and for inhibitory effect on HeLa cell macromol. synthesis, I exhibited strong cytotoxicity against the cells and inhibitory action on DNA synthesis.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL1cXltVOnt74%253D&md5=aa58f4ea0023074df4a08fbac085b3d6
    31. 31
      Koizumi, Y.; Tomoda, H.; Kumagai, A.; Zhou, X. P.; Koyota, S.; Sugiyama, T. Cancer Sci. 2009, 100, 322– 326,  DOI: 10.1111/j.1349-7006.2008.01033.x
      31
      Simaomicin α, a polycyclic xanthone, induces G1 arrest with suppression of retinoblastoma protein phosphorylation
      Koizumi, Yukio; Tomoda, Hiroshi; Kumagai, Ayako; Zhou, Xiao-ping; Koyota, Souichi; Sugiyama, Toshihiro
      Cancer Science (2009), 100 (2), 322-326CODEN: CSACCM; ISSN:1347-9032. (Wiley-Blackwell)
      Recent progress in cancer biol. research has shown that abnormal proliferation in tumor cells can be attributed to aberrations in cell cycle regulation, esp. in G1 phase. During the course of searching for microbial metabolites that affect cell cycle distribution, we have found that simaomicin α, a polycyclic xanthone antibiotic, arrests the cell cycle at G1 phase. Treatment of T-cell leukemia Jurkat cells with 3 nM simaomicin α induced an increase in the no. of cells in G1 and a decrease in those in G2-M phase. Cell cycle aberrations induced by simaomicin α were also detected in colon adenocarcinoma HCT15 cells. Simaomicin α had antiproliferative activities in various tumor cell lines with 50% inhibitory concn. values in the range of 0.3-19 nM. Furthermore, simaomicin α induced an increase in cellular caspase-3 activity and DNA fragmentation, indicating that simaomicin α promotes apoptosis. The retinoblastoma protein phosphorylation status of simaomicin α-treated cell lysate was lower than that of control cells, suggesting that the target mol. of simaomicin α is in a pathway upstream of retinoblastoma protein phosphorylation. In the course of evaluating polycyclic xanthone antibiotics structurally related to simaomicin α, we also found that cervinomycin A1 stimulated accumulation of treated cells in G1 phase. These results indicate that the polycyclic xanthones, including simaomicin α and cervinomycin A1, may be candidate cancer chemotherapeutic agents.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhvVylsL8%253D&md5=94c3c193912efe7ee1c10ee5696a83cb
    32. 32
      Zhang, W.; Wang, L.; Kong, L.; Wang, T.; Chu, Y.; Deng, Z.; You, D. Chem. Biol. 2012, 19, 422– 432,  DOI: 10.1016/j.chembiol.2012.01.016
      32
      Unveiling the post-PKS redox tailoring steps in biosynthesis of the type II polyketide antitumor antibiotic xantholipin
      Zhang, Weike; Wang, Lu; Kong, Lingxin; Wang, Tao; Chu, Yiwen; Deng, Zixin; You, Delin
      Chemistry & Biology (Oxford, United Kingdom) (2012), 19 (3), 422-432CODEN: CBOLE2; ISSN:1074-5521. (Elsevier Ltd.)
      Xantholipin from Streptomyces flavogriseus is a curved hexacyclic arom. polyketide antitumor antibiotic. The entire 52 kb xantholipin (xan) biosynthetic gene cluster was sequenced, and bioinformatic anal. revealed open reading frames encoding type II polyketide synthases, regulators, and polyketide tailoring enzymes. Individual in-frame mutagenesis of five tailoring enzymes lead to the prodn. of nine xantholipin analogs, revealing that the xanthone scaffold formation was catalyzed by the FAD binding monooxygenase XanO4, the δ-lactam formation by the asparagine synthetase homolog XanA, the methylenedioxy bridge generation by the P 450 monooxygenase XanO2 and the hydroxylation of the carbon backbone by the FAD binding monooxygenase XanO5. These findings may also apply to other polycyclic xanthone antibiotics, and they form the basis for genetic engineering of the xantholipin and similar biosynthetic gene clusters for the generation of compds. with improved antitumor activities.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XksFeisLc%253D&md5=db17ce4c8a5192387e112a0dd9890c2f
    33. 33
      Tanaka, H.; Kawakita, K.; Suzuki, H.; Spiri-Nakagawa, P.; Omura, S. J. Antibiot. 1989, 42, 431– 439,  DOI: 10.7164/antibiotics.42.431
      There is no corresponding record for this reference.
    34. 34
      Liu, L. L.; He, L. S.; Xu, Y.; Han, Z.; Li, Y. X.; Zhong, J. L.; Guo, X. R.; Zhang, X. X.; Ko, K. M.; Qian, P. Y. Chem. Res. Toxicol. 2013, 26, 1055– 1063,  DOI: 10.1021/tx4000304
      There is no corresponding record for this reference.
    35. 35
      Suzukake, K.; Hori, M. J. Antibiot. 1977, 30, 132– 140,  DOI: 10.7164/antibiotics.30.132
      There is no corresponding record for this reference.
    36. 36
      Müller, A.; Klöckner, A.; Schneider, T. Nat. Prod. Rep. 2017, 34, 909– 932,  DOI: 10.1039/C7NP00012J
      36
      Targeting a cell wall biosynthesis hot spot
      Mueller, Anna; Kloeckner, Anna; Schneider, Tanja
      Natural Product Reports (2017), 34 (7), 909-932CODEN: NPRRDF; ISSN:0265-0568. (Royal Society of Chemistry)
      A review on antibiotics. History points to the bacterial cell wall biosynthetic network as a very effective target for antibiotic intervention, and numerous natural product inhibitors have been discovered. In addn. to the inhibition of enzymes involved in the multistep synthesis of the macromol. layer, in particular, interference with membrane-bound substrates and intermediates essential for the biosynthetic reactions has proven a valuable antibacterial strategy. A prominent target within the peptidoglycan biosynthetic pathway is lipid II, which represents a particular "Achilles' heel" for antibiotic attack, as it is readily accessible on the outside of the cytoplasmic membrane. Lipid II is a unique non-protein target that is one of the structurally most conserved mols. in bacterial cells. Notably, lipid II is more than just a target mol., since sequestration of the cell wall precursor may be combined with addnl. antibiotic activities, such as the disruption of membrane integrity or disintegration of membrane-bound multi-enzyme machineries. Within the membrane bilayer lipid II is likely organized in specific anionic phospholipid patches that form a particular "landing platform" for antibiotics. Nature has invented a variety of different "lipid II binders" of at least 5 chem. classes, and their antibiotic activities can vary substantially depending on the compds.' physicochem. properties, such as amphiphilicity and charge, and thus trigger diverse cellular effects that are decisive for antibiotic activity.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFSls7rP&md5=6876099d28da5efd81da1855f7b8f683
    37. 37
      Medema, M. H.; Kottmann, R.; Yilmaz, P.; Cummings, M.; Biggins, J. B.; Blin, K.; de Bruijn, I.; Chooi, Y. H.; Claesen, J.; Coates, R. C.; Cruz-Morales, P.; Duddela, S.; Düsterhus, S.; Edwards, D. J.; Fewer, D. P.; Garg, N.; Geiger, C.; Gomez-Escribano, J. P.; Greule, A.; Hadjithomas, M.; Haines, A. S.; Helfrich, E. J.; Hillwig, M. L.; Ishida, K.; Jones, A. C.; Jones, C. S.; Jungmann, K.; Kegler, C.; Kim, H. U.; Kötter, P.; Krug, D.; Masschelein, J.; Melnik, A. V.; Mantovani, S. M.; Monroe, E. A.; Moore, M.; Moss, N.; Nützmann, H. W.; Pan, G.; Pati, A.; Petras, D.; Reen, F. J.; Rosconi, F.; Rui, Z.; Tian, Z.; Tobias, N. J.; Tsunematsu, Y.; Wiemann, P.; Wyckoff, E.; Yan, X.; Yim, G.; Yu, F.; Xie, Y.; Aigle, B.; Apel, A. K.; Balibar, C. J.; Balskus, E. P.; Barona-Gómez, F.; Bechthold, A.; Bode, H. B.; Borriss, R.; Brady, S. F.; Brakhage, A. A.; Caffrey, P.; Cheng, Y. Q.; Clardy, J.; Cox, R. J.; De Mot, R.; Donadio, S.; Donia, M. S.; van der Donk, W. A.; Dorrestein, P. C.; Doyle, S.; Driessen, A. J.; Ehling-Schulz, M.; Entian, K. D.; Fischbach, M. A.; Gerwick, L.; Gerwick, W. H.; Gross, H.; Gust, B.; Hertweck, C.; Höfte, M.; Jensen, S. E.; Ju, J.; Katz, L.; Kaysser, L.; Klassen, J. L.; Keller, N. P.; Kormanec, J.; Kuipers, O. P.; Kuzuyama, T.; Kyrpides, N. C.; Kwon, H. J.; Lautru, S.; Lavigne, R.; Lee, C. Y.; Linquan, B.; Liu, X.; Liu, W.; Luzhetskyy, A.; Mahmud, T.; Mast, Y.; Méndez, C.; Metsä-Ketelä, M.; Micklefield, J.; Mitchell, D. A.; Moore, B. S.; Moreira, L. M.; Müller, R.; Neilan, B. A.; Nett, M.; Nielsen, J.; O’Gara, F.; Oikawa, H.; Osbourn, A.; Osburne, M. S.; Ostash, B.; Payne, S. M.; Pernodet, J. L.; Petricek, M.; Piel, J.; Ploux, O.; Raaijmakers, J. M.; Salas, J. A.; Schmitt, E. K.; Scott, B.; Seipke, R. F.; Shen, B.; Sherman, D. H.; Sivonen, K.; Smanski, M. J.; Sosio, M.; Stegmann, E.; Süssmuth, R. D.; Tahlan, K.; Thomas, C. M.; Tang, Y.; Truman, A. W.; Viaud, M.; Walton, J. D.; Walsh, C. T.; Weber, T.; van Wezel, G. P.; Wilkinson, B.; Willey, J. M.; Wohlleben, W.; Wright, G. D.; Ziemert, N.; Zhang, C.; Zotchev, S. B.; Breitling, R.; Takano, E.; Glöckner, F. O. Nat. Chem. Biol. 2015, 11, 625– 631,  DOI: 10.1038/nchembio.1890
      37
      Minimum information about a biosynthetic gene cluster
      Medema, Marnix H.; Kottmann, Renzo; Yilmaz, Pelin; Cummings, Matthew; Biggins, John B.; Blin, Kai; de Bruijn, Irene; Chooi, Yit Heng; Claesen, Jan; Coates, R. Cameron; Cruz-Morales, Pablo; Duddela, Srikanth; Duesterhus, Stephanie; Edwards, Daniel J.; Fewer, David P.; Garg, Neha; Geiger, Christoph; Gomez-Escribano, Juan Pablo; Greule, Anja; Hadjithomas, Michalis; Haines, Anthony S.; Helfrich, Eric J. N.; Hillwig, Matthew L.; Ishida, Keishi; Jones, Adam C.; Jones, Carla S.; Jungmann, Katrin; Kegler, Carsten; Kim, Hyun Uk; Koetter, Peter; Krug, Daniel; Masschelein, Joleen; Melnik, Alexey V.; Mantovani, Simone M.; Monroe, Emily A.; Moore, Marcus; Moss, Nathan; Nuetzmann, Hans-Wilhelm; Pan, Guohui; Pati, Amrita; Petras, Daniel; Reen, F. Jerry; Rosconi, Federico; Rui, Zhe; Tian, Zhenhua; Tobias, Nicholas J.; Tsunematsu, Yuta; Wiemann, Philipp; Wyckoff, Elizabeth; Yan, Xiaohui; Yim, Grace; Yu, Fengan; Xie, Yunchang; Aigle, Bertrand; Apel, Alexander K.; Balibar, Carl J.; Balskus, Emily P.; Barona-Gomez, Francisco; Bechthold, Andreas; Bode, Helge B.; Borriss, Rainer; Brady, Sean F.; Brakhage, Axel A.; Caffrey, Patrick; Cheng, Yi-Qiang; Clardy, Jon; Cox, Russell J.; De Mot, Rene; Donadio, Stefano; Donia, Mohamed S.; van der Donk, Wilfred A.; Dorrestein, Pieter C.; Doyle, Sean; Driessen, Arnold J. M.; Ehling-Schulz, Monika; Entian, Karl-Dieter; Fischbach, Michael A.; Gerwick, Lena; Gerwick, William H.; Gross, Harald; Gust, Bertolt; Hertweck, Christian; Hoefte, Monica; Jensen, Susan E.; Ju, Jianhua; Katz, Leonard; Kaysser, Leonard; Klassen, Jonathan L.; Keller, Nancy P.; Kormanec, Jan; Kuipers, Oscar P.; Kuzuyama, Tomohisa; Kyrpides, Nikos C.; Kwon, Hyung-Jin; Lautru, Sylvie; Lavigne, Rob; Lee, Chia Y.; Linquan, Bai; Liu, Xinyu; Liu, Wen; Luzhetskyy, Andriy; Mahmud, Taifo; Mast, Yvonne; Mendez, Carmen; Metsae-Ketelae, Mikko; Micklefield, Jason; Mitchell, Douglas A.; Moore, Bradley S.; Moreira, Leonilde M.; Mueller, Rolf; Neilan, Brett A.; Nett, Markus; Nielsen, Jens; O'Gara, Fergal; Oikawa, Hideaki; Osbourn, Anne; Osburne, Marcia S.; Ostash, Bohdan; Payne, Shelley M.; Pernodet, Jean-Luc; Petricek, Miroslav; Piel, Joern; Ploux, Olivier; Raaijmakers, Jos M.; Salas, Jose A.; Schmitt, Esther K.; Scott, Barry; Seipke, Ryan F.; Shen, Ben; Sherman, David H.; Sivonen, Kaarina; Smanski, Michael J.; Sosio, Margherita; Stegmann, Evi; Suessmuth, Roderich D.; Tahlan, Kapil; Thomas, Christopher M.; Tang, Yi; Truman, Andrew W.; Viaud, Muriel; Walton, Jonathan D.; Walsh, Christopher T.; Weber, Tilmann; van Wezel, Gilles P.; Wilkinson, Barrie; Willey, Joanne M.; Wohlleben, Wolfgang; Wright, Gerard D.; Ziemert, Nadine; Zhang, Changsheng; Zotchev, Sergey B.; Breitling, Rainer; Takano, Eriko; Gloeckner, Frank Oliver
      Nature Chemical Biology (2015), 11 (9), 625-631CODEN: NCBABT; ISSN:1552-4450. (Nature Publishing Group)
      A review and discussion. A wide variety of enzymic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Min. Information about a Biosynthetic Gene cluster (MIBiG) data std.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlKntrjN&md5=3ca6fcc3bfb657101131b18411d5a4c6
    38. 38
      Mazza, P.; Monciardini, P.; Cavaletti, L.; Sosio, M.; Donadio, S. Microb. Ecol. 2003, 45, 362– 72,  DOI: 10.1007/s00248-002-2038-4
      38
      Diversity of Actinoplanes and Related Genera Isolated from an Italian Soil
      Mazza, P.; Monciardini, P.; Cavaletti, L.; Sosio, M.; Donadio, S.
      Microbial Ecology (2003), 45 (4), 362-372CODEN: MCBEBU; ISSN:0095-3628. (Springer-Verlag New York Inc.)
      Actinoplanes and related genera are good producers of bioactive secondary metabolites. However, many strains within these genera present similar morphol. characteristics, and this prevents an effective discrimination of replicate strains during industrial isolation and screening programs. Using PCR-RFLP anal. of the 23S rDNA gene and of the 16S-23S intergenic spacer, we have analyzed 182 strains of Actinoplanes and related genera obtained through a selective isolation method from a single Italian soil. Combining the 23S and IGS data, 99 unique profiles were obsd., and morphol. undistinguishable strains were discriminated. Further analyses on a restricted no. of strains through 16S sequencing and hybridization to a probe for secondary metab. established a good correlation between strain diversity seen by PCR-RFLP and that seen by the other methods. Overall, the data indicate the presence of a high diversity of Actinoplanes and related genera isolated from a single Italian soil.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3sXksFWms78%253D&md5=a8f35f4ce647904e7be060e1b62081ae
    39. 39
      Weber, T.; Blin, K.; Duddela, S.; Krug, D.; Kim, H. U.; Bruccoleri, R.; Lee, S. Y.; Fischbach, M. A.; Müller, R.; Wohlleben, W.; Breitling, R.; Takano, E.; Medema, M. H. Nucleic Acids Res. 2015, 43, W237– 43,  DOI: 10.1093/nar/gkv437
      39
      antiSMASH 3.0-a comprehensive resource for the genome mining of biosynthetic gene clusters
      Weber, Tilmann; Blin, Kai; Duddela, Srikanth; Krug, Daniel; Kim, Hyun Uk; Bruccoleri, Robert; Lee, Sang Yup; Fischbach, Michael A.; Muller, Rolf; Wohlleben, Wolfgang; Breitling, Rainer; Takano, Eriko; Medema, Marnix H.
      Nucleic Acids Research (2015), 43 (W1), W237-W243CODEN: NARHAD; ISSN:0305-1048. (Oxford University Press)
      Microbial secondary metab. constitutes a rich source of antibiotics, chemotherapeutics, insecticides and other high-value chems. Genome mining of gene clusters that encode the biosynthetic pathways for these metabolites has become a key methodol. for novel compd. discovery. In 2011, we introduced antiSMASH, a web server and stand-alone tool for the automatic genomic identification and anal. of biosynthetic gene clusters, available at http://antismash.secondarymetabolites.org. Here, we present version 3.0 of antiSMASH, which has undergone major improvements. A full integration of the recently published ClusterFinder algorithm now allows using this probabilistic algorithm to detect putative gene clusters of unknown types. Also, a new dereplication variant of the ClusterBlast module now identifies similarities of identified clusters to any of 1172 clusters with known end products. At the enzyme level, active sites of key biosynthetic enzymes are now pinpointed through a curated pattern-matching procedure and Enzyme Commission nos. are assigned to functionally classify all enzyme-coding genes. Addnl., chem. structure prediction has been improved by incorporating polyketide redn. states. Finally, in order for users to be able to organize and analyze multiple antiSMASH outputs in a private setting, a new XML output module allows offline editing of antiSMASH annotations within the Geneious software.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVymtbzN&md5=03415650d89df1a3a1c812be313af9a1

  • Supporting Information

    Supporting Information

    ARTICLE SECTIONS
    Jump To

    The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jnatprod.8b00354.

    • Experimental Section; characteristics of enduracyclinone-producing strains; reporter gene induction assay; time-kill data; cytotoxicity data; macromolecular syntheses inhibition data; 13C–15N enrichment data; NMR spectra (PDF)


    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

PDF [ 2MB]

Pair your accounts.

Export articles to Mendeley

Get article recommendations from ACS based on references in your Mendeley library.

Pair your accounts.

Export articles to Mendeley

Get article recommendations from ACS based on references in your Mendeley library.

You’ve supercharged your research process with ACS and Mendeley!

STEP 1:
Click to create an ACS ID

Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

MENDELEY PAIRING EXPIRED
Your Mendeley pairing has expired. Please reconnect