title: Involvement of GDH3-encoded NADP+-dependent glutamate dehydrogenase in yeast cell resistance to stress-induced apoptosis in stationary phase cells.
abstract: Glutamate metabolism is linked to a number of fundamental metabolic pathways such as amino acid metabolism, the TCA cycle, and glutathione (GSH) synthesis. In the yeast Saccharomyces cerevisiae, glutamate is synthesized from α-ketoglutarate by two NADP(+)-dependent glutamate dehydrogenases (NADP-GDH) encoded by GDH1 and GDH3. Here, we report the relationship between the function of the NADP-GDH and stress-induced apoptosis. Gdh3-null cells showed accelerated chronological aging and hypersusceptibility to thermal and oxidative stress during stationary phase. Upon exposure to oxidative stress, Gdh3-null strains displayed a rapid loss in viability associated with typical apoptotic hallmarks, i.e. reactive oxygen species accumulation, nuclear fragmentation, DNA breakage, and phosphatidylserine translocation. In addition, Gdh3-null cells, but not Gdh1-null cells, had a higher tendency toward GSH depletion and subsequent reactive oxygen species accumulation than did WT cells. GSH depletion was rescued by exogenous GSH or glutamate. The hypersusceptibility of stationary phase Gdh3-null cells to stress-induced apoptosis was suppressed by deletion of GDH2. Promoter swapping and site-directed mutagenesis of GDH1 and GDH3 indicated that the necessity of GDH3 for the resistance to stress-induced apoptosis and chronological aging is due to the stationary phase-specific expression of GDH3 and concurrent degradation of Gdh1 in which the Lys-426 residue plays an essential role.
authors.affiliation: Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Yong Joo
authors.initials: YJ
authors.lastname: Lee
authors.forename: Kyung Jin
authors.initials: KJ
authors.lastname: Kim
authors.forename: Hong Yong
authors.initials: HY
authors.lastname: Kang
authors.forename: Hye-Rim
authors.initials: HR
authors.lastname: Kim
authors.forename: Pil Jae
authors.initials: PJ
authors.lastname: Maeng
mesh_terms: D017209:Apoptosis; D015966:Gene Expression Regulation, Fungal; D018086:Glutamate Dehydrogenase (NADP+) / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D018384:Oxidative Stress; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D018698:Glutamic Acid; C579079:GDH3 protein, S cerevisiae; D018086:Glutamate Dehydrogenase (NADP+)