title: Characterization of ypa1 and ypa2, the Schizosaccharomyces pombe orthologs of the peptidyl proyl isomerases that activate PP2A, reveals a role for Ypa2p in the regulation of cytokinesis.
abstract: The Schizosaccharomyces pombe septation initiation network (SIN) regulates cytokinesis. Cdc7p is the first kinase in the core SIN; we have screened genetically for SIN regulators by isolating cold-sensitive suppressors of cdc7-24. Our screen yielded a mutant in SPAC1782.05, one of the two fission yeast orthologs of mammalian phosphotyrosyl phosphatase activator. We have characterized this gene and its ortholog SPAC4F10.04, which we have named ypa2 and ypa1, respectively. We find that Ypa2p is the major form of protein phosphatase type 2A activator in S. pombe. A double ypa1-Δ ypa2-Δ null mutant is inviable, indicating that the two gene products have at least one essential overlapping function. Individually, the ypa1 and ypa2 genes are essential for survival only at low temperatures. The ypa2-Δ mutant divides at a reduced cell size and displays aberrant cell morphology and cytokinesis. Genetic analysis implicates Ypa2p as an inhibitor of the septation initiation network. We also isolated a cold-sensitive allele of ppa2, the major protein phosphatase type 2A catalytic subunit, implicating this enzyme as a regulator of the septation initiation network.
authors.affiliation: School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
authors.forename: Anupama
authors.initials: A
authors.lastname: Goyal
authors.forename: Viesturs
authors.initials: V
authors.lastname: Simanis
mesh_terms: D000705:Anaphase; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D003080:Cold Temperature; D048749:Cytokinesis; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D025941:Protein Interaction Mapping; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism; D013172:Spores, Fungal / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; C113816:Sid2 protein, S pombe; C489406:cdc7 protein, S pombe; D017346:Protein Serine-Threonine Kinases; D054648:Protein Phosphatase 2; D019696:Peptidylprolyl Isomerase