Role of Tos3, a Snf1 protein kinase kinase, during growth of Saccharomyces cerevisiae on nonfermentable carbon sources

Eukaryot Cell. 2005 May;4(5):861-6. doi: 10.1128/EC.4.5.861-866.2005.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cytosol / enzymology
  • Gluconeogenesis
  • Promoter Regions, Genetic / genetics
  • Protein Kinases / genetics
  • Protein Kinases / physiology*
  • Protein Serine-Threonine Kinases / metabolism*
  • Response Elements / genetics
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / growth & development*
  • Saccharomyces cerevisiae Proteins
  • Sequence Deletion

Substances

  • Saccharomyces cerevisiae Proteins
  • Protein Kinases
  • SNF1-related protein kinases
  • Protein Serine-Threonine Kinases
  • TOS3 protein, S cerevisiae