Abstract
Eukaryotic cell proliferation is controlled by growth factors and essential nutrients. In their absence, cells may enter into a quiescent state (G0). In Saccharomyces cerevisiae, the conserved protein kinase A (PKA) and rapamycin-sensitive TOR (TORC1) pathways antagonize G0 entry in response to carbon and/or nitrogen availability primarily by inhibiting the PAS kinase Rim15 function. Here, we show that the phosphate-sensing Pho80-Pho85 cyclin-cyclin-dependent kinase (CDK) complex also participates in Rim15 inhibition through direct phosphorylation, thereby effectively sequestering Rim15 in the cytoplasm via its association with 14-3-3 proteins. Inactivation of either Pho80-Pho85 or TORC1 causes dephosphorylation of the 14-3-3-binding site in Rim15, thus enabling nuclear import of Rim15 and induction of the Rim15-controlled G0 program. Importantly, we also show that Pho80-Pho85 and TORC1 converge on a single amino acid in Rim15. Thus, Rim15 plays a key role in G0 entry through its ability to integrate signaling from the PKA, TORC1, and Pho80-Pho85 pathways.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
14-3-3 Proteins / metabolism
-
Active Transport, Cell Nucleus
-
Binding Sites
-
Cell Nucleus / metabolism
-
Cyclic AMP-Dependent Protein Kinases / metabolism
-
Cyclin-Dependent Kinases / chemistry
-
Cyclin-Dependent Kinases / metabolism*
-
Cyclins / chemistry*
-
Cyclins / metabolism
-
Cytoplasm / metabolism
-
Glutathione Transferase / metabolism
-
Green Fluorescent Proteins / metabolism
-
Immunoblotting
-
Immunoprecipitation
-
Models, Biological
-
Mutation
-
Phosphatidylinositol 3-Kinases / metabolism
-
Phosphorylation
-
Phosphotransferases (Alcohol Group Acceptor) / metabolism
-
Plasmids / metabolism
-
Protein Binding
-
Protein Kinases / metabolism
-
Protein Structure, Tertiary
-
Repressor Proteins / chemistry*
-
Resting Phase, Cell Cycle*
-
Saccharomyces cerevisiae / metabolism
-
Saccharomyces cerevisiae Proteins / chemistry*
-
Saccharomyces cerevisiae Proteins / metabolism
-
Signal Transduction
-
TOR Serine-Threonine Kinases
-
Time Factors
Substances
-
14-3-3 Proteins
-
Cyclins
-
PHO80 protein, S cerevisiae
-
Repressor Proteins
-
Saccharomyces cerevisiae Proteins
-
Green Fluorescent Proteins
-
Glutathione Transferase
-
Protein Kinases
-
Phosphotransferases (Alcohol Group Acceptor)
-
Rim15 protein, S cerevisiae
-
TOR1 protein, S cerevisiae
-
TOR Serine-Threonine Kinases
-
Cyclic AMP-Dependent Protein Kinases
-
Cyclin-Dependent Kinases
-
PHO85 protein, S cerevisiae