Role of Tos3, a Snf1 protein kinase kinase, during growth of Saccharomyces cerevisiae on nonfermentable carbon sources.
In Saccharomyces cerevisiae, Snf1 protein kinase of the Snf1/AMP-activated protein kinase family is required for growth on nonfermentable carbon sources and nonpreferred sugars. Three kinases, Pak1, Elm1, and Tos3, activate Snf1 by phosphorylation of its activation-loop threonine, and the absence of all three causes the Snf(-) phenotype. No phenotype has previously been reported for the tos3Delta single mutation. We show here that, when cells are grown on glycerol-ethanol, tos3Delta reduces growth rate, Snf1 catalytic activity, and activation of the Snf1-dependent carbon source-responsive element (CSRE) in the promoters of gluconeogenic genes. In contrast, tos3Delta did not significantly affect Snf1 catalytic activity or CSRE function during abrupt glucose depletion, indicating that Tos3 has a more substantial role in activating Snf1 protein kinase during growth on a nonfermentable carbon source than during acute carbon stress. We also report that Tos3 is localized in the cytosol during growth in either glucose or glycerol-ethanol. These findings lend support to the idea that the Snf1 protein kinase kinases make different contributions to cellular regulation under different growth conditions.
Kim
Myoung-Dong
MD
Department of Genetics and Development and Microbiology, Columbia University, HSC922, New York, NY 10032, USA. mbc1@columbia.edu
Hong
Seung-Pyo
SP
Carlson
Marian
M
D003600:Cytosol / Q000201:enzymology; D005943:Gluconeogenesis; D011401:Promoter Regions, Genetic / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion
D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; C502450:TOS3 protein, S cerevisiae