Eukaryotic membrane lipids create hydrophobic physical barriers which control information and substance exchange between the outside and inside of cells and also between different cellular compartments. Membrane lipids like... more
Eukaryotic membrane lipids create hydrophobic physical barriers which control information and substance exchange between the outside and inside of cells and also between different cellular compartments. Membrane lipids like Phosphoinositides (PIs) also exert regulatory ef fect on cells in addition to its membrane traf ficking property. Apart from that, phosphoinositide specific phospholipase C (PI-PLC), the enzyme acting upon phosphoinositides, also plays a significant role in exerting such regulatory effect on cell functions. PI-PLCs belong to an important class of enzymes and involved in lipid signalling. The functional mechanism of PI-PLCs is well studied in animal system. Certainly , it is evident that phosphoinositides and phospholipase C both play key roles in plant growth, development and stress tolerance. However, an exact mechanism pertaining to the action of the role of PI-PLC is still under elucidation. In this communication, an attempt has been made to highlight the mechanism of regulation in pla t PI-PLCs and to revisit the area of functioning of PIs and PI-PLCs in response to biotic and in particular abiotic stresses in plants.
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Chemistry and Signalling
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The negative effects of soil salinity towards grape yield depend upon salt concentration, cultivar type, developmental stage, and rootstock. Thompson Seedless variety of grape plant is considered moderately sensitive to salinity when... more
The negative effects of soil salinity towards grape yield depend upon salt concentration, cultivar type, developmental stage, and rootstock. Thompson Seedless variety of grape plant is considered moderately sensitive to salinity when grown upon its own root stock. In recent epoch, identification of key genes responsive to salinity offers hope to generate salinity-tolerant crop plants by their overexpression through genetic manipulation. In the present report, salt responsive transcriptome analysis of Thompson Seedless grape variety was done to identify vital genes involved in salinity tolerance which could be used further to generate salt liberal grape plant or other crop plants. Transcriptome libraries for control and 150-mM-NaCl-treated grape leaves were sequenced on Illumina platform where 714 genes were found to be differentially expressed. Gene ontology analysis indicated that under salinity conditions, the genes involved in metabolic process were highly enriched. Keto Encyclop...
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Dehydrins, PpDHNA and PpDHNB from Physcomitrella patens provide drought and cold tolerance while PpDHNC shows antimicrobial property suggesting different dehydrins perform separate functions in P. patens. The moss Physcomitrella patens... more
Dehydrins, PpDHNA and PpDHNB from Physcomitrella patens provide drought and cold tolerance while PpDHNC shows antimicrobial property suggesting different dehydrins perform separate functions in P. patens. The moss Physcomitrella patens can withstand extremes of environmental condition including abiotic stress such as dehydration, salinity, low temperature and biotic stress such as pathogen attack. Osmotic stress is inflicted under both cold and drought stress conditions where dehydrins have been found to play a significant protective role. In this study, a comparative analysis was drawn for the three dehydrins PpDHNA, PpDHNB and PpDHNC from P. patens. Our data shows that PpDHNA and PpDHNB play a major role in cellular protection during osmotic stress. PpDHNB showed several fold upregulation of the gene when P. patens was subjected to cold and osmotic stress in combination. PpDHNA and PpDHNB provide protection to enzyme lactate dehydrogenase under osmotic as well as freezing conditio...
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Life is characterized by complex organization, precise regulation, and colorful diversity. It is a biochemical system that is always far from thermodynamic equilibrium. The maintenance of such a state demands a constant expenditure of... more
Life is characterized by complex organization, precise regulation, and colorful diversity. It is a biochemical system that is always far from thermodynamic equilibrium. The maintenance of such a state demands a constant expenditure of energy to maintain a unidirectional flow of metabolites. A network of anabolic and catabolic pathways operates in every living cell. It is well known that phosphate esters in living organisms are essential intermediates in metabolic transformations and these phosphorylated compounds are invariably associated with energy balance, which is fundamental to life processes. The sources of energy for living organisms are extremely diverse, but it is not clear why phosphate esters rather than the esters of other inorganic acids predominate in biological systems. It is probably significant that phosphate anhydrides combine high activation energies of nonenzymatic hydrolysis with large negative free energies of hydrolysis. This permits controlled enzymatic cleavage of the anhydride, rather than spontaneous hydrolysis. Lipmann (1951) has pointed out that acetic anhydride is hydrolyzed rapidly in neutral conditions, acetylphosphate is more stable, and pyrophosphate is resistant to hydrolysis at neutral pH. Phosphates are probably protected from hydroxyl attack by their negative charge. The discussion in this chapter is centered around a biologically important phosphocompound that was discovered as early as 1872 by Pfeffer (1872). This was subsequently identified as a salt of phytic acid (or more correctly myo-inositol hexakisphosphate), which is the major phosphorus constituent of cereal grain (Williams, 1970).
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1L-myo-Inositol-1-phosphate synthase catalyzes the conversion of D-glucose 6-phosphate to 1L-myo-inositol-1-phosphate, the first committed step in the production of all inositol-containing compounds, including phospholipids, either... more
1L-myo-Inositol-1-phosphate synthase catalyzes the conversion of D-glucose 6-phosphate to 1L-myo-inositol-1-phosphate, the first committed step in the production of all inositol-containing compounds, including phospholipids, either directly or by salvage. The enzyme exists in a cytoplasmic form in a wide range of plants, animals, and fungi. It has also been detected in several bacteria and a chloroplast form is observed in alga and higher plants. The enzyme has been purified from a wide range of organisms and its active form is a multimer of identical subunits ranging in molecular weight from 58,000 to 67,000. The activity of the synthase is stimulated by NH4Cl and inhibited by glucitol 6-phosphate and 2-deoxyglucose 6-phosphate. Structural genes (INO1) encoding the 1L-myo-inositol-1-phosphate synthase subunit have been isolated from several eukaryotic microorganisms and higher plants. In baker's yeast, Saccharomyces cerevisiae, the transcriptional regulation of the INO1 gene has been studied in detail and its expression is sensitive to the availability of phospholipid precursors as well as growth phase. The regulation of the structural gene encoding 1L-myo-inositol-1-phosphate synthase has also been analyzed at the transcriptional level in the aquatic angiosperm, Spirodela polyrrhiza and the halophyte, Mesembryanthemum crystallinum.
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Page 1. Chapter 16 Osmolyte Regulation in Abiotic Stress Arun Lahiri Majumder, Sonali Sengupta, and Lily Goswami Plant Molecular and Cellular Genetics, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata 700 054, India Summary ...
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... above 60 C) having an optimal enzyme activity at around 85 C. Subsequently, several otherarchaebacterial sources have been ... Till date over 70 Ino1 genes have been reported from evolutionarily diverse organ-isms, both prokaryotic... more
... above 60 C) having an optimal enzyme activity at around 85 C. Subsequently, several otherarchaebacterial sources have been ... Till date over 70 Ino1 genes have been reported from evolutionarily diverse organ-isms, both prokaryotic and eukaryotic (Table 2 ...
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The pathway from glucose 6-phosphate (G 6-P) to myoinositol 1-phosphate (Ins 1-P) and myo-inositol (Ins) is essential for the synthesis of various metabolites. In the halophyte Mesembryanthemum crystallinum (common ice plant), two... more
The pathway from glucose 6-phosphate (G 6-P) to myoinositol 1-phosphate (Ins 1-P) and myo-inositol (Ins) is essential for the synthesis of various metabolites. In the halophyte Mesembryanthemum crystallinum (common ice plant), two enzymes, myo-inositol O-methyltransferase (IMT1) and ononitol epimerase (OEP1), extend this pathway and lead to the accumulation of methylated inositols, D-ononitol and D-pinitol, which serve as osmoprotectants. This paper describes transcripts for the enzyme, Inps1, encoding myo-inositol 1-phosphate synthase (INPS1), from the ice plant. Two Inps-like sequences are present in the genome. The deduced amino acid sequences of the cloned transcript are 49.5% and 87-90%, respectively, identical to those of yeast and other higher plant sequences. Inps1 RNA amounts are upregulated at least fivefold and amounts of free Ins accumulate approximately 10-fold during salinity stress. Inps1 induction is by transcription, similar to the induction of Imt1. In contrast, Arabidopsis thaliana does not show upregulation of Inps1 or increased amounts of Ins when salt-stressed. The lack of Inps1 induction in Arabidopsis exemplifies differences in glycophytic and halophytic regulation of gene expression at the point of entry into a pathway that leads to osmoprotection. The stress-induced coordinate upregulation of this pathway and its extension by novel enzymes in the ice plant also highlights biochemical differences.
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Biochemistry, Metabolism, Plant Biology, Biology, Medicine, and 15 moreGene expression, Arabidopsis thaliana, Osmoregulation, Salinity, Methylation, Plant, Homology, Osmotic pressure, Plants, Inositol, Arabidopsis, Environmental Stress, Amino Acid Sequence, Base Sequence, and Molecular Sequence Data
L-myo-inositol 1-phosphate synthase (EC 5.5.1.4; MIPS) catalyzes conversion of glucose 6-phosphate to L-myo-inositol 1-phosphate, the first and the rate-limiting step in the production of inositol, and has been reported from... more
L-myo-inositol 1-phosphate synthase (EC 5.5.1.4; MIPS) catalyzes conversion of glucose 6-phosphate to L-myo-inositol 1-phosphate, the first and the rate-limiting step in the production of inositol, and has been reported from evolutionarily diverse organisms. Two forms of the enzyme have been characterized from higher plants, viz. cytosolic and chloroplastic, and the presence of MIPS has been earlier reported from the cyanobacteria (e.g. Spirulina sp.), the presumed chloroplast progenitors. The present study demonstrates possible multiple forms of MIPS and identifies the gene for one of them in the cyanobacterium Synechocystis sp. PCC 6803. Following detection of at least two immunologically cross-reactive MIPS forms, we have been able to identify from the fully sequenced Synechocystis genome an as yet unassigned open reading frame (ORF), sll1722, coding for the approx. 50-kDa MIPS protein, by using biochemical, molecular and bioinformatics tools. The DNA fragment corresponding to sll1722 was PCR-amplified and functional identity of the gene was confirmed by a complementation assay in Saccharomyces cerevisiae mutants containing a disrupted INO1 gene for the yeast MIPS. The sll1722 PCR product was cloned in Escherichia coli expression vector pET20b and the isopropyl beta-D-thiogalactopyranoside (IPTG)-induced overexpressed protein product was characterized following complete purification. Comparison of the sll1722 sequences with other MIPS sequences and its phylogenetic analysis revealed that the Synechocystis MIPS gene is quite divergent from the others.
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Biochemistry, Plant Biology, Biology, Cyanobacteria, Medicine, and 15 moreSaccharomyces cerevisiae, Phylogeny, Sequence alignment, Escherichia coli, ATP synthase, Phylogenetic analysis, Gene, Enzyme, Amino Acid Sequence, Open Reading Frame, PLANT PROTEINS, Planta, DNA fragmentation, Molecular Sequence Data, and Rate Limiting
The gene coding for rice chloroplastic L-myo-inositol-1-phosphate synthase (MIPS; EC 5.5.1.4) has been identified by matrix-assisted laser desorption time-of-flight mass spectrometry analysis of the purified and immunologically... more
The gene coding for rice chloroplastic L-myo-inositol-1-phosphate synthase (MIPS; EC 5.5.1.4) has been identified by matrix-assisted laser desorption time-of-flight mass spectrometry analysis of the purified and immunologically cross-reactive approximately 60 kDa chloroplastic protein following two-dimensional polyacrylamide gel electrophoresis, which exhibited sequence identity with the cytosolic MIPS coded by OsINO1-1 gene. A possible chloroplastic transit peptide sequence was identified upstream of the OsINO1-1 gene upon analysis of rice genome. RT-PCR and confocal microscope studies confirmed transcription, effective translation and its functioning as a chloroplast transit peptide. Bioinformatic analysis mapped the chloroplastic MIPS (OsINO1-1) gene on chromosome 3, and a second MIPS gene (OsINO1-2) on chromosome 10 which lacks conventional chloroplast transit peptide sequence as in OsINO1-1. Two new PcINO1 genes, with characteristic promoter activity and upstream cis-elements were identified and cloned, but whether these proteins can be translocated to the chloroplast or not is yet to be ascertained. Electrophoretic mobility shift assay carried out with nuclear extract of Porteresia coarctata leaves grown under both control and stressed condition shows binding of nuclear proteins with the upstream elements. Nucleotide divergence among the different Oryza and Porteresia INO1 genes were calculated and compared.
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Biochemistry, Bioinformatics, Plant Biology, Biology, Medicine, and 15 moreGene expression, Crystal structure, Maldi Tof, Polymerase Chain Reaction, ATP synthase, Peptides, Phylogenetic analysis, Inositol, Enzyme, Amino Acid Profile, Molecular weight, Amino Acid Sequence, Chloroplast, Planta, and Molecular Sequence Data
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... IP4Inositol tetraphosphate. 324 ARUN LAHIRI MAJUMDER and BB BISWAs Behavior of the ... J. 66, 404 (1957). LN GIBBINS and FW NORRIS, Biochem. J. 86, 67 (1963). 9 A. M MAYER, Enzymologia 19, 1 (1958) io DR ERGLE and G. GUINN, Plant... more
... IP4Inositol tetraphosphate. 324 ARUN LAHIRI MAJUMDER and BB BISWAs Behavior of the ... J. 66, 404 (1957). LN GIBBINS and FW NORRIS, Biochem. J. 86, 67 (1963). 9 A. M MAYER, Enzymologia 19, 1 (1958) io DR ERGLE and G. GUINN, Plant Physiol. 34, 476 (1959). ...
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... Award" to one of us (ALM). References Adhikari, J. & Majumder, AL 1983. Differences in thermal stability of the fetal and adult brain myo-inositol-1-phosphate synthase: Probable involvement of NAD. - FEBS... more
... Award" to one of us (ALM). References Adhikari, J. & Majumder, AL 1983. Differences in thermal stability of the fetal and adult brain myo-inositol-1-phosphate synthase: Probable involvement of NAD. - FEBS Lett. 163: 46-49. Barnett, JEG, Brice, RE & Corina, DL 1970. ...
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L-myo-inositol 1phosphate synthase (EC 5.5.1.4 ; MIPS), an evolutionarily conserved enzyme-protein, catalyses the first and rate limiting step of inositol biosynthesis. Inositol and its derivatives play important roles in biological... more
L-myo-inositol 1phosphate synthase (EC 5.5.1.4 ; MIPS), an evolutionarily conserved enzyme-protein, catalyses the first and rate limiting step of inositol biosynthesis. Inositol and its derivatives play important roles in biological kingdom like growth regulation, ...
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ABSTRACT Emergence of high-throughput sequencing tools and omics technologies paved the way for systems biology in last decade. While we have started to look at the biology of the plant in a more unified manner, the integration of such... more
ABSTRACT Emergence of high-throughput sequencing tools and omics technologies paved the way for systems biology in last decade. While we have started to look at the biology of the plant in a more unified manner, the integration of such knowledge in agricultural biotechnology has become an arena of potential interest. The network of several central molecules operating in various life and developmental processes are now more adequately known, and fine tuning of such molecule pools, if connected to stress response, can result in enhanced stress tolerance of plants.This review interprets the potential of manipulation of myo-inositol and its derivatives in generation of transgenic crop plants. Being a molecule of central importance in plant life, inositol is connected to numerous life processes. The exploration of such pathways indicates that inositol itself and many of its derivatives can impart abiotic stress tolerance (against salinity, dehydration, chilling or oxidative stress) to plants when overexpressed. We propose that engineering inositol metabolic network is a potential approach towards stress-tolerant transgenic crop plant generation and thus its exploitation in agricultural biotechnology is the call of time.
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Biochemistry, Chemistry, Biology, Cyanobacteria, Oxidative Stress, and 15 moreMedicine, Escherichia coli, Polymerase Chain Reaction, Iron, Biochemical, Ion Exchange Chromatography, Paraquat, Hydrogen Peroxide, Superoxide, Growth Inhibition, Recombinant Protein, Heterologous Expression, Recombinant Proteins, Biochemistry and cell biology, and Medical biochemistry and metabolomics
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Some areas in plant abiotic stress research are not frequently addressed by genomic and molecular tools. One such area is the cross reaction of gravitational force with upward capillary pull of water and the mechanical-functional... more
Some areas in plant abiotic stress research are not frequently addressed by genomic and molecular tools. One such area is the cross reaction of gravitational force with upward capillary pull of water and the mechanical-functional trade-off in plant vasculature. Although frost, drought and flooding stress greatly impact these physiological processes and consequently plant performance, the genomic and molecular basis of such trade-off is only sporadically addressed and so is its adaptive value. Embolism resistance is an important multiple stress- opposition trait and do offer scopes for critical insight to unravel and modify the input of living cells in the process and their biotechnological intervention may be of great importance. Vascular plants employ different physiological strategies to cope with embolism and variation is observed across the kingdom. The genomic resources in this area have started to emerge and open up possibilities of synthesis, validation and utilization of the...
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Molecular Evolution, Biological Sciences, Saccharomyces cerevisiae, Phylogeny, Escherichia coli, and 15 moreAnimals, Phylogenetic analysis, Inositol, Enzyme, Molecular cloning, Entamoeba histolytica, Amino Acid Profile, Amino Acid Sequence, Base Sequence, Open Reading Frame, Bovine Serum Albumin, L, Nucleotides, Molecular Sequence Data, and Medical and Health Sciences
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Fructose-1,6-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase; EC 3.1.3.11) has been found in rat brain and identified unequivocally. The enzyme has been purified to 95% homogeneity by standard procedures, including... more
Fructose-1,6-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase; EC 3.1.3.11) has been found in rat brain and identified unequivocally. The enzyme has been purified to 95% homogeneity by standard procedures, including adsorption to a phosphocellulose column followed by elution with substrate. The purified enzyme exhibits a broad optimum above pH 7.6. Both fructose 1,6-bisphosphate and sedoheptulose 1,7-bisphosphate are substrates of this enzyme; the hydrolysis of the latter occurs at about 20% of the rate of the former, and the Km for fructose 1,6-bisphosphate is approximately 1.32 X 10(-4) M. 5'-AMP, an inhibitor of other mammalian-fructose-1,6-bisphosphatases, is without effect, and in further contrast with the other enzymes there is no metal requirement for activity. Purified brain enzyme fails to crossreact with the antibody prepared against the purified liver fructose-1,6-bisphosphatase. On the other hand, antiserum produced against the brain fructose-1,6-bispho...
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Kinetics, Plant Biology, Biology, Lithium, Medicine, and 15 morePhylogeny, Magnesium, Enzyme, Molecular cloning, Substrate Specificity, Enzyme activity, Metal ion, Genome sequence, Amino Acid Sequence, Open Reading Frame, Recombinant Protein, Recombinant Proteins, Planta, Molecular Sequence Data, and Synechocystis
Methylated inositol D-pinitol (3-O-methyl-D-chiro-inositol) accumulates in a number of plants naturally or in response to stress. Here, we present evidence for accumulation and salt-enhanced synthesis of pinitol in Porteresia coarctata, a... more
Methylated inositol D-pinitol (3-O-methyl-D-chiro-inositol) accumulates in a number of plants naturally or in response to stress. Here, we present evidence for accumulation and salt-enhanced synthesis of pinitol in Porteresia coarctata, a halophytic wild rice, in contrast to its absence in domesticated rice. A cDNA for Porteresia coarctata inositol methyl transferase 1 (PcIMT1), coding for the inositol methyl transferase implicated in the synthesis of pinitol has been cloned from P. coarctata, bacterially overexpressed and shown to be functional in vitro. In silico analysis confirms the absence of an IMT1 homolog in Oryza genome, and PcIMT1 is identified as phylogenetically remotely related to the methyl transferase gene family in rice. Both transcript and proteomic analysis show the up-regulation of PcIMT1 expression following exposure to salinity. Coordinated expression of L-myo-inositol 1-phosphate synthase (PcINO1) gene along with PcIMT1 indicates that in P. coarctata, accumulation of pinitol via inositol is a stress-regulated pathway. The presence of pinitol synthesizing protein/gene in a wild halophytic rice is remarkable, although its exact role in salt tolerance of P. coarctata cannot be currently ascertained. The enhanced synthesis of pinitol in Porteresia under stress may be one of the adaptive features employed by the plant in addition to its known salt-exclusion mechanism.
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The molecular basis of salt tolerance of l-myo-inositol 1-P synthase (MIPS; EC 5.5.1.4) from Porteresia coarctata (Roxb.) Tateoka (PcINO1, AF412340) earlier reported from this laboratory, has been analyzed by in vitro mutant and hybrid... more
The molecular basis of salt tolerance of l-myo-inositol 1-P synthase (MIPS; EC 5.5.1.4) from Porteresia coarctata (Roxb.) Tateoka (PcINO1, AF412340) earlier reported from this laboratory, has been analyzed by in vitro mutant and hybrid generation and subsequent biochemical and biophysical studies of the recombinant proteins. A 37-amino acid stretch between Trp-174 and Ser-210 has been confirmed as the salt-tolerance determinant domain in PcINO1 both by loss or gain of salt tolerance by either deletion or by addition to salt-sensitive MIPS(s) of Oryza (OsINO1) and Brassica juncea (BjINO1). This was further verified by growth analysis under salt environment of Schizosaccharomyces pombe transformed with the various gene constructs and studies on the differential behavior of mutant and wild proteins by Trp fluorescence, aggregation, and circular dichroism spectra in the presence of salt. 4,4′-Dianilino-1,1′-binaphthyl-5,5-disulfonic acid binding experiments revealed a lower hydrophobic ...