title: spo12 is a multicopy suppressor of mcs3 that is periodically expressed in fission yeast mitosis.
abstract: Hyperactivation of Cdc2 in fission yeast causes cells to undergo a lethal premature mitosis, a phenomenon called mitotic catastrophe. This phenotype is observed in cdc2-3w wee1-50 cells at high temperature and is suppressed by a single recessive mutant, mcs3-12. Mcs3 acts independently of the Wee1 kinase and Cdc25 phosphatase, two major regulators of Cdc2. We have isolated multicopy suppressors of the cell cycle arrest phenotype of mcs3-12 wee1-50 cdc25-22 cells, but did not identify the mcs3 gene itself. Instead several known mitotic regulators were isolated, including the Cdc25 phosphatase, Wis2 cyclophilin, Cek1 kinase, and an Hsp90 homologue, Swo1. We also isolated clones encoding non-functional, truncated forms of the Wee1 kinase and Dis2 type 1 phosphatase. In addition we identified a multicopy suppressor that encodes a structural homologue of the budding yeast SPO12 gene. We find that overexpression of fission yeast spo12 not only suppresses the phenotype of the mcs3-12 wee1-50 cdc25-22 strain, but also that of a win1-1 wee1-50 cdc25-22 strain at high temperature, indicating that the function of spo12 is not directly related to mcs3. We show that spo12 mRNA is periodically expressed during the fission yeast cell cycle, peaking at the G2/M transition coincidently with cdc15. Deletion of spo12, however, has no overt effect on either the mitotic or meiotic cell cycles, except when the function of the major B type cyclin, Cdc13, is compromised.
authors.affiliation: Division of Yeast Genetics, National Institute of Medical Research, Mill Hill, London, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Samuel
authors.forename: N
authors.initials: N
authors.lastname: Fournier
authors.forename: V
authors.initials: V
authors.lastname: Simanis
authors.forename: J B
authors.initials: JB
authors.lastname: Millar
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics*; D019926:Cyclin B / Q000235:genetics; D004251:DNA Transposable Elements; D005656:Fungal Proteins / Q000235:genetics*; D017353:Gene Deletion; D016153:Genes, Suppressor; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics; D008938:Mitosis / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D010957:Plasmids / Q000378:metabolism; D054645:Protein Phosphatase 1; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic; D013696:Temperature; D013997:Time Factors
chemical_list: D018797:Cell Cycle Proteins; D019926:Cyclin B; D004251:DNA Transposable Elements; D005656:Fungal Proteins; D018841:HSP90 Heat-Shock Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C091275:Swo1 protein, S pombe; C499614:spo12 protein, S pombe; C077339:CEK1 protein, Candida albicans; C068689:wee1 protein, S pombe; D011505:Protein-Tyrosine Kinases; D016203:CDC2 Protein Kinase; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C092048:GLC7 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1