Cdc28 and Cdc14 control stability of the anaphase-promoting complex inhibitor Acm1.
The anaphase-promoting complex (APC) regulates the eukaryotic cell cycle by targeting specific proteins for proteasomal degradation. Its activity must be strictly controlled to ensure proper cell cycle progression. The co-activator proteins Cdc20 and Cdh1 are required for APC activity and are important regulatory targets. Recently, budding yeast Acm1 was identified as a Cdh1 binding partner and APC(Cdh1) inhibitor. Acm1 disappears in late mitosis when APC(Cdh1) becomes active and contains conserved degron-like sequences common to APC substrates, suggesting it could be both an inhibitor and substrate. Surprisingly, we found that Acm1 proteolysis is independent of APC. A major determinant of Acm1 stability is phosphorylation at consensus cyclin-dependent kinase sites. Acm1 is a substrate of Cdc28 cyclin-dependent kinase and Cdc14 phosphatase both in vivo and in vitro. Mutation of Cdc28 phosphorylation sites or conditional inactivation of Cdc28 destabilizes Acm1. In contrast, inactivation of Cdc14 prevents Acm1 dephosphorylation and proteolysis. Cdc28 stabilizes Acm1 in part by promoting binding of the 14-3-3 proteins Bmh1 and Bmh2. We conclude that the opposing actions of Cdc28 and Cdc14 are primary factors limiting Acm1 to the interval from G(1)/S to late mitosis and are capable of establishing APC-independent expression patterns similar to APC substrates.
Hall
Mark C
MC
Biochemistry Department, Purdue Cancer Center, and Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907, USA. mchall@purdue.edu
Jeong
Dah-Eun
DE
Henderson
James T
JT
Choi
Eunyoung
E
Bremmer
Steven C
SC
Iliuk
Anton B
AB
Charbonneau
Harry
H
D048948:14-3-3 Proteins / Q000378:metabolism; D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D017489:CDC28 Protein Kinase, S cerevisiae / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D008938:Mitosis; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D017027:Protein Tyrosine Phosphatases / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*; D043743:Ubiquitin-Protein Ligase Complexes
D048948:14-3-3 Proteins; C516306:Acm1 protein, S cerevisiae; C075852:BMH1 protein, S cerevisiae; C097164:BMH2 protein, S cerevisiae; C074860:CDC14 protein, S cerevisiae; D018797:Cell Cycle Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D017489:CDC28 Protein Kinase, S cerevisiae; D017027:Protein Tyrosine Phosphatases