Abstract
Beta-oxidation (beta-ox) occurs exclusively in the peroxisomes of Saccharomyces cerevisiae and other yeasts, leading to the supposition that fungi lack mitochondrial beta-ox. Here we present unequivocal evidence that the filamentous fungus Aspergillus nidulans houses both peroxisomal and mitochondrial beta-ox. While growth of a peroxisomal beta-ox disruption mutant (DeltafoxA) was eliminated on a very long-chain fatty acid (C(22:1)), growth was only partially impeded on a long-chain fatty acid (C(18:1)) and was not affected at all on short chain (C4-C6) fatty acids. In contrast, growth of a putative enoyl-CoA hydratase mutant (DeltaechA) was abolished on short-chain and severely restricted on long- and very long-chain fatty acids. Furthermore fatty acids inhibited growth of the DeltaechA mutant but not the DeltafoxA mutant in the presence of an alternate carbon source (lactose). Disruption of echA led to a 28-fold reduction in 2-butenoyl-CoA hydratase activity in a preparation of organelles. EchA was also required for growth on isoleucine and valine. The subcellular localization of the FoxA and EchA proteins was confirmed through the use of red and green fluorescent protein fusions.
Publication types
- Research Support, U.S. Gov't, P.H.S.
MeSH terms
- Acyl Coenzyme A / metabolism
- Aspergillus nidulans / chemistry
- Aspergillus nidulans / enzymology*
- Aspergillus nidulans / growth & development
- Aspergillus nidulans / metabolism
- Enoyl-CoA Hydratase / genetics
- Enoyl-CoA Hydratase / physiology
- Fatty Acids / metabolism*
- Fungal Proteins / genetics
- Fungal Proteins / isolation & purification
- Fungal Proteins / metabolism
- Gene Deletion
- Genes, Fungal
- Genes, Reporter
- Green Fluorescent Proteins / analysis
- Green Fluorescent Proteins / genetics
- Isoleucine / metabolism
- Lactose / metabolism
- Luminescent Proteins / analysis
- Luminescent Proteins / genetics
- Mitochondria / enzymology*
- Mitochondria / metabolism
- Mitochondrial Trifunctional Protein
- Multienzyme Complexes / genetics
- Multienzyme Complexes / isolation & purification*
- Multienzyme Complexes / metabolism
- Oxidation-Reduction
- Peroxisomes / enzymology
- Peroxisomes / metabolism
- Recombinant Fusion Proteins / analysis
- Recombinant Fusion Proteins / genetics
- Red Fluorescent Protein
- Valine / metabolism
Substances
- Acyl Coenzyme A
- Fatty Acids
- Fungal Proteins
- Luminescent Proteins
- Multienzyme Complexes
- Recombinant Fusion Proteins
- Isoleucine
- Green Fluorescent Proteins
- 2-butynoyl-coenzyme A
- Mitochondrial Trifunctional Protein
- Enoyl-CoA Hydratase
- Valine
- Lactose