title: Role of Gts1p in regulation of energy-metabolism oscillation in continuous cultures of the yeast Saccharomyces cerevisiae.
abstract: Energy-metabolism oscillation (EMO) in an aerobic chemostat culture of yeast is basically regulated by a feedback loop of redox reactions in energy metabolism and modulated by metabolism of storage carbohydrates. In this study, we investigated the role of Gts1p in the stabilization of EMO, using the GTS1-deleted transformant gts1Delta. We found that fluctuations in the redox state of the NAD co-factor and levels of redox-regulated metabolites in glycolysis, especially of ethanol, are markedly reduced in amplitude during EMO of gts1Delta, while respiration indicated by the oxygen uptake rate (OUR) and energy charge is not so affected throughout EMO in gts1Delta. Further, the transitions of the levels of OUR, NAD(+) : NADH ratio and intracellular pH between the two phases were apparently retarded compared with those in the wild-type, suggesting attenuation of EMO in gts1Delta. Furthermore, the mRNA levels of genes encoding enzymes for the synthesis of trehalose and glycogen are fairly reduced in gts1Delta, consistent with the decreased synthesis of storage carbohydrates. In addition, the level of inorganic phosphate, which is required for the reduction of NAD(+) and mainly supplied from trehalose synthesis, was decreased in the early respiro-fermentative phase in gts1Delta. Thus, we suggested that the deletion of GTS1 as a transcriptional co-activator for these genes inhibited the metabolism of storage carbohydrates, which causes attenuation of the feedback loop of dehydrogenase reactions in glycolysis with the restricted fluctuation of ethanol as a main synchronizing agent for EMO in a cell population.
authors.affiliation: Department of Biochemistry 2, University of Yamanashi, Faculty of Medicine, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Xu
authors.forename: Kunio
authors.initials: K
authors.lastname: Tsurugi
mesh_terms: D000332:Aerobiosis; D001683:Biological Clocks; D050260:Carbohydrate Metabolism; D004734:Energy Metabolism; D000431:Ethanol / Q000378:metabolism; D017353:Gene Deletion; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis; D016695:Glycosyltransferases / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D014199:Trehalose / Q000378:metabolism
chemical_list: C097841:GTS1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D009243:NAD; D000431:Ethanol; D006003:Glycogen; D014199:Trehalose; D016695:Glycosyltransferases; D010100:Oxygen