title: Fission yeast MAP kinase is required for the increased securin-separase interaction that rescues separase mutants under stresses.
abstract: Sister chromatid separation requires two steps of proteolysis. Securin, the chaperon and inhibitor of separase, is destructed in anaphase after polyubiquitination, and resulting activated separase cleaves the cohesin subunit Scc1/Rad21. Fission yeast securin/Cut2 and separase/Cut1 that form the complex are essential for viability and a number of temperature-sensitive (ts) mutants have been isolated. We here report that the stresses such as 1.2 M sorbitol, 0.6 M KCl and 0.1 M CaCl(2) in the medium suppress the ts phenotypes of all the cut1 mutants and two of the three cut2 mutants examined. This unexpected finding led us to study how the ts phenotypes of cut1 and cut2 mutants were rescued by the increased stresses. The stresses caused a temporal arrest in the cell number increase, and this arrest was dependent on Spc1/Sty1 but not Rad3 and Mad2. During the 2-3 hr arrested period that occurred prior to the restart of division cycle, the level of securin dramatically increased, apparently accompanying the increased complex formation with mutant separase protein. Securin bound to separase was hyperphosphorylated. The stresses could not rescue the indestructible Cut2 and Rad21 mutants. We postulate that the stresses produce the hyperchaperonic form of Cut2 that can rescue separase mutations.
authors.affiliation: Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kawasaki
authors.forename: Koji
authors.initials: K
authors.lastname: Nagao
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakamura
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yanagida
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D006982:Hypertonic Solutions; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D009997:Osmotic Pressure; D010641:Phenotype; D010766:Phosphorylation; D011189:Potassium Chloride / Q000494:pharmacology; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D064249:Securin; D013012:Sorbitol / Q000494:pharmacology; D013696:Temperature; D000097722:Cohesins
chemical_list: D002122:Calcium Chloride; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D017868:Cyclic AMP-Dependent Protein Kinases; D006982:Hypertonic Solutions; D020928:Mitogen-Activated Protein Kinases; D009687:Nuclear Proteins; D011189:Potassium Chloride; D029702:Schizosaccharomyces pombe Proteins; D064249:Securin; D013012:Sorbitol; D000097722:Cohesins; C103135:Cut1 protein, S pombe; C103136:Cut2 protein, S pombe; C540907:psm1 protein, S pombe; C095409:sty1 protein, S pombe