title: Redox responses in yeast to acetate as the carbon source.
abstract: Following a shift to medium with acetate as the carbon source, a parental yeast strain exhibited a transient moderate 20% reduction in total cellular [NAD(+)+NADH] but showed a approximately 10-fold increase in the ratio of [NAD(+)]:[NADH] after 36h. A mutant strain (idhDelta) lacking the tricarboxylic acid cycle enzyme isocitrate dehydrogenase had 50% higher cellular levels of [NAD(+)+NADH] relative to the parental strain but exhibited similar changes in cofactor concentrations following a shift to acetate medium, despite an inability to grow on that carbon source; essentially all of the cofactor was in the oxidized form within 36h. The salvage pathway for NAD(H) biosynthesis was found to be particularly important for viability during early transition of the parental strain to stationary phase in acetate medium. However, oxygen consumption was not affected, suggesting that the NAD(H) produced during this time may support other cellular functions. The idhDelta mutant exhibited increased flux through the salvage pathway in acetate medium but was dependent on the de novo pathway for viability. Long-term chronological lifespans of the parental and idhDelta strains were similar, but viability of the mutant strain was dependent on both pathways for NAD(H) biosynthesis.
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center, San Antonio, 78229-3900, USA.
authors.forename: Karyl I
authors.initials: KI
authors.lastname: Minard
authors.forename: L
authors.initials: L
authors.lastname: McAlister-Henn
mesh_terms: D019342:Acetic Acid / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D002952:Citric Acid Cycle; D003470:Culture Media; D005800:Genes, Fungal; D005947:Glucose / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009243:NAD / Q000378:metabolism; D009535:Nicotinamidase / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D000098553:Nicotinate-Nucleotide Diphosphorylase (Carboxylating)
chemical_list: D003470:Culture Media; D029701:Saccharomyces cerevisiae Proteins; D009243:NAD; D002244:Carbon; D007521:Isocitrate Dehydrogenase; D010430:Pentosyltransferases; D000098553:Nicotinate-Nucleotide Diphosphorylase (Carboxylating); D009535:Nicotinamidase; C474330:PNC1 protein, S cerevisiae; D005947:Glucose; D019342:Acetic Acid