title: Phosphatase 2A negatively regulates mitotic exit in Saccharomyces cerevisiae.
abstract: In budding yeast Saccharomyces cerevisiae, Cdc5 kinase is a component of mitotic exit network (MEN), which inactivates cyclin-dependent kinase (CDK) after chromosome segregation. cdc5-1 mutants arrest at telophase at the nonpermissive temperature due to the failure of CDK inactivation. To identify more negative regulators of MEN, we carried out a genetic screen for genes that are toxic to cdc5-1 mutants when overexpressed. Genes that encode the B-regulatory subunit (Cdc55) and the three catalytic subunits (Pph21, Pph22, and Pph3) of phosphatase 2A (PP2A) were isolated. In addition to cdc5-1, overexpression of CDC55, PPH21, or PPH22 is also toxic to other temperature-sensitive mutants that display defects in mitotic exit. Consistently, deletion of CDC55 partially suppresses the temperature sensitivity of these mutants. Moreover, in the presence of spindle damage, PP2A mutants display nuclear localized Cdc14, the key player in MEN pathway, indicative of MEN activation. All the evidence suggests the negative role of PP2A in mitotic exit. Finally, our genetic and biochemical data suggest that PP2A regulates the phosphorylation of Tem1, which acts at the very top of MEN pathway.
authors.affiliation: Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA. yanchang.wang@med.fsu.edu
authors.forename: Yanchang
authors.initials: Y
authors.lastname: Wang
authors.forename: Tuen-Yung
authors.initials: TY
authors.lastname: Ng
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005804:Genes, Lethal / Q000235:genetics; D008938:Mitosis; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: C473476:Amn1 protein, S cerevisiae; C119117:BFA1 protein, S cerevisiae; C070351:BUB2 protein, S cerevisiae; C074860:CDC14 protein, S cerevisiae; C071246:CDC55 protein, S cerevisiae; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C081927:CDC5 protein, S cerevisiae; D054648:Protein Phosphatase 2; D010744:Phosphoric Monoester Hydrolases; D017027:Protein Tyrosine Phosphatases; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1