title: PSK2 coordinates glucose metabolism and utilization to maintain ultradian clock-coupled respiratory oscillation in Saccharomyces cerevisiae yeast.
abstract: Ultradian clock-coupled respiratory oscillation (UCRO) in an aerobic continuous culture of Saccharomyces cerevisiae S288C is principally regulated by control of certain redox reactions of energy metabolism. It is also modulated by the metabolism of storage carbohydrates during adaptation to environmental change. However, the mechanism of cell sensing and response to environmental nutrients in UCRO is unknown. The purpose of the present study was to determine the role of PSK2 kinase in UCRO in yeast. S. cerevisiae in culture showed oscillation in PSK2 mRNA levels with a definite phase relationship to the respiratory oscillation. Furthermore, inactivation of Psk2 by gene disruption severely affected UCRO and its decline to undetectable levels within 2days. In addition, the extracellular and intracellular glucose concentrations of PSK2 deletion mutants in culture were higher and lower, respectively, than those of the wild type. PSK2 mutant cells showed no alteration in redox state. Furthermore, the levels of storage carbohydrates such as glycogen and trehalose fluctuated in PSK2 mutants with attenuated amplitudes comparable to those in the wild type. The results indicated that PSK2 kinase is important for the uptake of glucose and regulation of storage-carbohydrate synthesis and hence the maintenance of an unperturbed continuously oscillating state.
authors.affiliation: Department of Biochemistry 2, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi 409-3898, Japan.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Ouyang
authors.forename: Qinghong
authors.initials: Q
authors.lastname: Xu
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Mitsui
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Motizuki
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Xu
mesh_terms: D001683:Biological Clocks; D050260:Carbohydrate Metabolism; D005947:Glucose / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; C467889:PSK2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D005947:Glucose