期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 108, 期 16, 页码 6349-6354出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1102758108
关键词
glucose regulation; signal transduction; yeast
资金
- Fulbright
- National Institutes of Health [GM34095]
The SNF1 protein kinase of Saccharomyces cerevisiae is a member of the SNF1/AMP-activated protein kinase family, which is essential for metabolic control, energy homeostasis, and stress responses in eukaryotes. SNF1 is activated in response to glucose limitation by phosphorylation of Thr210 on the activation loop of the catalytic subunit Snf1. The SNF1 beta-subunit contains a glycogen-binding domain that has been implicated in glucose inhibition of Snf1 Thr210 phosphorylation. To assess the role of glycogen, we examined Snf1 phosphorylation in strains with altered glycogen metabolism. A reg1 Delta mutant, lacking Reg1-Glc7 protein phosphatase 1, exhibits elevated glycogen accumulation and phosphorylation of Snf1 during growth on high levels of glucose. Unexpectedly, mutations that abolished glycogen synthesis also restored Thr210 dephosphorylation in glucose-grown reg1 Delta cells, indicating that elevated glycogen synthesis contributes to activation of SNF1 and that another phosphatase acts on Snf1. We present evidence that Sit4, a type 2A-like protein phosphatase, contributes to dephosphorylation of Snf1 Thr210. Finally, evidence that the effects of glycogen are not mediated by binding to the beta-subunit raises the possibility that elevated glycogen synthesis alters glucose metabolism and thereby reduces glucose signaling to the SNF1 pathway.
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