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Role of Gts1p in regulation of energy‐metabolism oscillation in continuous cultures of the yeast Saccharomyces cerevisiae
Author(s) -
Xu Zhaojun,
Tsurugi Kunio
Publication year - 2007
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.1468
Subject(s) - nad+ kinase , chemostat , biology , trehalose , biochemistry , saccharomyces cerevisiae , metabolism , glycolysis , redox , dehydrogenase , oxidative phosphorylation , cellular respiration , population , biophysics , yeast , enzyme , mitochondrion , chemistry , genetics , bacteria , demography , organic chemistry , sociology
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 gts1 Δ. 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 gts1 Δ, while respiration indicated by the oxygen uptake rate (OUR) and energy charge is not so affected throughout EMO in gts1 Δ. 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 gts1 Δ. Furthermore, the mRNA levels of genes encoding enzymes for the synthesis of trehalose and glycogen are fairly reduced in gts1 Δ, 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 gts1 Δ. 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. Copyright © 2007 John Wiley & Sons, Ltd.