title: Ultradian rhythm of trehalose levels coupled to heat resistance in continuous cultures of the yeast Saccharomyces cerevisiae.
abstract: Heat resistance appears to cycle in concert with energy metabolism in continuous culture of the yeast Saccharomyces cerevisiae. To study the mechanism of this oscillation, the authors first examined if heat shock proteins (Hsps) are involved. Neither the protein levels of major Hsps nor the expression of the beta-galactosidase gene as a reporter under the control of the promoter carrying heat-shock element oscillated during the metabolic oscillation. The level of trehalose in yeast cycled with the same periodicity, as did energy metabolism. This oscillation was not found in a GTS1-deleted mutant that also did not show cyclic changes in heat resistance. These results suggest that heat resistance oscillation is induced by fluctuations in trehalose level and not by an oscillatory expression of Hsps. The increase in trehalose began at the start of the respiro-fermentative phase and the decrease began after the elevation of the cyclic adenosine monophosphate (cAMP) level. The authors hypothesize that the synthesis of trehalose parallels the activation of the glycolytic pathway and that trehalose is degraded by trehalase activated by cAMP coupled with the metabolic oscillation in the continuous culture of yeast.
authors.affiliation: Department of Internal Medicine 2, Yamanashi Medical University, Tamaho, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Uno
authors.forename: Jinqing
authors.initials: J
authors.lastname: Wang
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Mitsui
authors.forename: Ken
authors.initials: K
authors.lastname: Umetani
authors.forename: Kohji
authors.initials: K
authors.lastname: Tamura
authors.forename: Kunio
authors.initials: K
authors.lastname: Tsurugi
mesh_terms: D000204:Activity Cycles / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D004734:Energy Metabolism; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D017930:Genes, Reporter; D006360:Heat-Shock Proteins / Q000378:metabolism; D006358:Hot Temperature; D007763:Lac Operon; D008954:Models, Biological; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D014157:Transcription Factors; D014199:Trehalose / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; C097841:GTS1 protein, S cerevisiae; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014199:Trehalose; D000242:Cyclic AMP