| New insights into {gamma}-aminobutyric acid catabolism: Evidence for {gamma}-hydroxybutyric acid and polyhydroxybutyrate synthesis in Saccharomyces cerevisiae. | |
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MedLine Citation:
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PMID: 19411412 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The gamma-aminobutyrate (GABA) shunt, an alternative route for the conversion of alpha-ketoglutarate to succinate, involves the glutamate decarboxylase Gad1p, the GABA transaminase Uga1p and the succinate semialdehyde dehydrogenase Uga2p. This pathway has been extensively described in plants and animals, but its function in yeast remains unclear. We show that the flux through Gad1p is insignificant during fermentation in rich sugar-containing medium, excluding a role for this pathway in redox homeostasis under anaerobic conditions or sugar stress. However, we found that up to 4 g of exogenous GABA/liter was efficiently consumed by yeast. We studied the fate of this consumed GABA. Most was converted into succinate, with a reaction yield of 0.7 mol/mol. We also showed that a large proportion of GABA was stored within cells, indicating a possible role for this molecule in stress tolerance mechanisms or nitrogen storage. Furthermore, based on enzymatic and metabolic evidence, we identified an alternative route for GABA catabolism, involving the reduction of succinate-semialdehyde into gamma-hydroxybutyric acid and the polymerization of gamma-hydroxybutyric acid to form poly-(3-hydroxybutyric acid-co-4-hydroxybutyric acid). This study provides the first demonstration of a native route for the formation of this polymer in yeast. Our findings shed new light on the GABA pathway and open up new opportunities for industrial applications. |
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Authors:
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Benoît Bach; Emmanuelle Meudec; Jean-Paul Lepoutre; Tristan Rossignol; Bruno Blondin; Sylvie Dequin; Carole Camarasa |
Publication Detail:
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Type: Journal Article Date: 2009-05-01 |
Journal Detail:
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Title: Applied and environmental microbiology Volume: 75 ISSN: 1098-5336 ISO Abbreviation: Appl. Environ. Microbiol. Publication Date: 2009 Jul |
Date Detail:
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Created Date: 2009-06-26 Completed Date: 2009-08-11 Revised Date: 2010-09-27 |
Medline Journal Info:
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Nlm Unique ID: 7605801 Medline TA: Appl Environ Microbiol Country: United States |
Other Details:
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Languages: eng Pagination: 4231-9 Citation Subset: IM |
Affiliation:
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UMR Sciences pour l'Oenologie, INRA, Montpellier, France. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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4-Aminobutyrate Transaminase
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metabolism Fermentation Glutamate Decarboxylase / metabolism Hydroxybutyrates / metabolism* Ketoglutaric Acids / metabolism Metabolic Networks and Pathways Models, Biological Polyesters / metabolism* Saccharomyces cerevisiae / metabolism* Saccharomyces cerevisiae Proteins / metabolism Succinate-Semialdehyde Dehydrogenase (NADP+) / metabolism Succinic Acid / metabolism gamma-Aminobutyric Acid / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Hydroxybutyrates; 0/Ketoglutaric Acids; 0/Polyesters; 0/Saccharomyces cerevisiae Proteins; 0/poly(4-hydroxybutanoate); 110-15-6/Succinic Acid; 26063-00-3/poly-beta-hydroxybutyrate; 56-12-2/gamma-Aminobutyric Acid; 591-81-1/4-hydroxybutyric acid; EC 1.2.1.16/Succinate-Semialdehyde Dehydrogenase (NADP+); EC 1.2.1.16/UGA2 protein, S cerevisiae; EC 2.6.1.19/4-Aminobutyrate Transaminase; EC 4.1.1.15/Glutamate Decarboxylase; EC 4.1.1.15/glutamate decarboxylase 1 |
| Comments/Corrections | |
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