Hexokinase 2 from Saccharomyces cerevisiae: Regulation of Oligomeric Structure by in Vivo Phosphorylation at Serine-14

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• 作者：Joachim Behlke ; Katja Heidrich ; Manfred Naumann ; Eva-Christina Mü ; ller ; Albrecht Otto ; Renate Reuter ; and Thomas Kriegel
• 刊名：Biochemistry
• 出版年：1998
• 出版时间：August 25, 1998
• 年：1998
• 卷：37
• 期：34
• 页码：11989 - 11995
• 全文大小：75K
• 年卷期：v.37,no.34(August 25, 1998)
• ISSN：1520-4995

文摘

Homodimeric hexokinase 2 from Saccharomyces cerevisiae is known to have two sites ofphosphorylation: for serine-14 the modification in vivo increases with glucose exhaustion [Kriegel et al.(1994) Biochemistry 33, 148-152], while for serine-157 it occurs in vitro with ATP in the presence ofnonphosphorylateable five-carbon analogues of glucose [Heidrich et al. (1997) Biochemistry 36, 1960-1964]. We show now by site-directed mutagenesis and sedimentation analysis that serine-14 phosphorylation affects the oligomeric state of hexokinase, its substitution by glutamate causing completedissociation; glutamate exchange for serine-157 does not. Phosphorylation of wild-type hexokinase atserine-14 likewise causes dissociation in vitro. In view of the higher glucose affinity of monomerichexokinase and the high hexokinase concentration in yeast [Womack, F., and Colowick, S. P. (1978)Arch. Biochem. Biophys. 191, 742-747; Mayes, E. L., Hoggett, J. G., and Kellett, G. L. (1983) Eur. J.Biochem. 133, 127-134], we speculate that the in vivo phosphorylation at serine-14 as transiently occurringin glucose derepression might provide a mechanism to improve glucose utilization from low level and/orthat nuclear localization of the monomer might be involved in the signal transduction whereby glucosecauses catabolite repression.