title: Gts1p stabilizes oscillations in energy metabolism by activating the transcription of TPS1 encoding trehalose-6-phosphate synthase 1 in the yeast Saccharomyces cerevisiae.
abstract: We reported previously that Gts1p regulates oscillations of heat resistance in concert with those of energy metabolism in continuous cultures of the yeast Saccharomyces cerevisiae by inducing fluctuations in the levels of trehalose, but not in those of Hsp104 (heat shock protein 104). Further, the expression of TPS1, encoding trehalose-6-phosphate synthase 1, and HSP104 was activated by Gts1p in combination with Snf1 kinase, a transcriptional activator of glucose-repressible genes, in batch cultures under derepressed conditions. Here we show that, in continuous cultures, the mRNA level of TPS1 increased 6-fold in the early respiro-fermentative phase, while that of HSP104 did not change. The expression of SUC2, a representative glucose-repressible gene encoding invertase, also fluctuated, suggesting the involvement of the Snf1 kinase in the periodic activation of these genes. However, this possibility was proven to be unlikely, since the oscillations in both TPS1 and SUC2 mRNA expression were reduced by approx. 3-fold during the transient oscillation in gts1Delta (GTS1-deleted) cells, in which the energy state determined by extracellular glucose and intracellular adenine nucleotide levels was comparable with that in wild-type cells. Furthermore, neither the mRNA level nor the phosphorylation status of Snf1p changed significantly during the oscillation. Thus we suggest that Gts1p plays a major role in the oscillatory expression of TPS1 and SUC2 in continuous cultures of Saccharomyces cerevisiae, and hypothesized that Gts1p stabilizes oscillations in energy metabolism by activating trehalose synthesis to facilitate glycolysis at the shift from the respiratory to the respiro-fermentative phase.
authors.affiliation: Department of Biochemistry 2, University of Yamanashi, Faculty of Medicine, 1110 Shimokato, Tamaho, Yamanashi 409-3898, Japan.
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Xu
authors.forename: So-ichi
authors.initials: S
authors.lastname: Yaguchi
authors.forename: Kunio
authors.initials: K
authors.lastname: Tsurugi
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D004734:Energy Metabolism / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D005964:Glucosyltransferases / Q000096:biosynthesis* / Q000235:genetics; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology; D043324:beta-Fructofuranosidase / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000227:Adenine Nucleotides; C097841:GTS1 protein, S cerevisiae; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C070972:HsP104 protein, S cerevisiae; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; C468437:SUC2 protein, S cerevisiae; D043324:beta-Fructofuranosidase