Synergistic inhibition of APC/C by glucose and activated Ras proteins can be mediated by each of the Tpk1-3 proteins in Saccharomyces cerevisiae.
Proteolysis triggered by the anaphase-promoting complex/cyclosome (APC/C) is essential for the progression through mitosis. APC/C is a highly conserved ubiquitin ligase whose activity is regulated during the cell cycle by various factors, including spindle checkpoint components and protein kinases. The cAMP-dependent protein kinase (PKA) was identified as negative regulator of APC/C in yeast and mammalian cells. In the yeast Saccharomyces cerevisiae, PKA activity is induced upon glucose addition or by activated Ras proteins. This study shows that glucose and the activated Ras2(Val19) protein synergistically inhibit APC/C function via the cAMP/PKA pathway in yeast. Remarkably, Ras2 proteins defective in the interaction with adenylate cyclase fail to influence APC/C, implying that its function is regulated exclusively by PKA, but not by alternative Ras pathways. Furthermore, it is shown that the three PKAs in yeast, Tpk1, Tpk2 and Tpk3, have redundant functions in regulating APC/C in response to glucose medium. Single or double deletions of TPK genes did not prevent inhibition of APC/C, suggesting that each of the Tpk proteins can take over this function. However, Tpk2 seems to inhibit APC/C function more efficiently than Tpk1 and Tpk3. Finally, evidence is provided that Cdc20 is involved in APC/C regulation by the cAMP/PKA pathway.
Institute of Microbiology and Genetics, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
Melanie
M
Bolte
Institute of Microbiology and Genetics, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
Patrick
P
Dieckhoff
Institute of Microbiology and Genetics, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
Cindy
C
Krause
Institute of Microbiology and Genetics, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
Gerhard H
GH
Braus
Institute of Microbiology and Genetics, Georg-August-University, Grisebachstr. 8, D-37077 Göttingen, Germany.
Stefan
S
Irniger
D064173:Anaphase-Promoting Complex-Cyclosome; D002453:Cell Cycle; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000494:pharmacology*; D008025:Ligases / Q000037:antagonists & inhibitors* / Q000235:genetics; D009154:Mutation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes; D018631:ras Proteins / Q000378:metabolism / Q000494:pharmacology*
D003470:Culture Media; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D000242:Cyclic AMP; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D011494:Protein Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; C457179:TPK2 protein, S cerevisiae; C489015:RAS2 protein, S cerevisiae; D018631:ras Proteins; D008025:Ligases; D005947:Glucose