title: Redundant Regulation of Cdk1 Tyrosine Dephosphorylation in Saccharomyces cerevisiae.
abstract: Cdk1 activity drives both mitotic entry and the metaphase-to-anaphase transition in all eukaryotes. The kinase Wee1 and the phosphatase Cdc25 regulate the mitotic activity of Cdk1 by the reversible phosphorylation of a conserved tyrosine residue. Mutation of cdc25 in Schizosaccharomyces pombe blocks Cdk1 dephosphorylation and causes cell cycle arrest. In contrast, deletion of MIH1, the cdc25 homolog in Saccharomyces cerevisiae, is viable. Although Cdk1-Y19 phosphorylation is elevated during mitosis in mih1∆ cells, Cdk1 is dephosphorylated as cells progress into G1, suggesting that additional phosphatases regulate Cdk1 dephosphorylation. Here we show that the phosphatase Ptp1 also regulates Cdk1 dephosphorylation in vivo and can directly dephosphorylate Cdk1 in vitro. Using a novel in vivo phosphatase assay, we also show that PP2A bound to Rts1, the budding yeast B56-regulatory subunit, regulates dephosphorylation of Cdk1 independently of a function regulating Swe1, Mih1, or Ptp1, suggesting that PP2A(Rts1) either directly dephosphorylates Cdk1-Y19 or regulates an unidentified phosphatase.
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada.
authors.forename: Erin K
authors.initials: EK
authors.lastname: Kennedy
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Dysart
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada.
authors.forename: Noel
authors.initials: N
authors.lastname: Lianga
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Williams
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada.
authors.forename: Sophie
authors.initials: S
authors.lastname: Pilon
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada.
authors.forename: Carole
authors.initials: C
authors.lastname: Doré
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada.
authors.forename: Jean-Sebastien
authors.initials: JS
authors.lastname: Deneault
authors.affiliation: Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, ON K1H 8M5, Canada arudner@uottawa.ca.
authors.forename: Adam D
authors.identifier: http://orcid.org/0000-0002-0301-1042
authors.initials: AD
authors.lastname: Rudner
mesh_terms: D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry*; D020666:ras-GRF1 / Q000235:genetics / Q000378:metabolism
chemical_list: C542351:CDC25 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D020666:ras-GRF1; D014443:Tyrosine; D016203:CDC2 Protein Kinase; D054648:Protein Phosphatase 2; C584366:Rts1 protein, S cerevisiae; D017027:Protein Tyrosine Phosphatases
keywords: Cdc25/Mih1; Cdk1; PP2A; Wee1/Swe1; mitosis