title: Fission yeast mfr1 activates APC and coordinates meiotic nuclear division with sporulation.
abstract: Meiosis is the developmental program by which sexually reproducing diploid organisms generate haploid gametes. In yeast, meiosis is followed by spore morphogenesis. These two events are normally coordinated in such a way that spore formation is dependent upon completion of the meiotic nuclear divisions. Here we describe a meiosis-specific protein, mfr1, that is involved in this coordination. mfr1 is an activator of the anaphase-promoting complex (APC), which is necessary for the rapid degradation of the cdc13 cyclin at the end of meiosis II, prior to the formation of spores. An mfr1 null mutant completes meiosis II but remains with high levels of cdc13 and cdc2 kinase activity and has considerably delayed spore formation. By analogy with the mitotic cell cycle, where proteolysis and inactivation of cdc2 kinase are necessary to trigger mitotic exit and cytokinesis, we propose that at the end of meiosis rapid and timely proteolysis of cyclins is required to switch on the differentiation program that eventually leads to the formation of haploid gametes.
authors.affiliation: Instituto de Microbiología Bioquímica, CSIC/Universidad de Salamanca, Edificio Departamental, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Blanco
authors.forename: L
authors.initials: L
authors.lastname: Pelloquin
authors.forename: S
authors.initials: S
authors.lastname: Moreno
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism; D002455:Cell Division; D003001:Cloning, Molecular; D019926:Cyclin B / Q000378:metabolism; D005434:Flow Cytometry; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D008540:Meiosis; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D011233:Precipitin Tests; D011485:Protein Binding; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases
chemical_list: C577515:Ama1 protein, S cerevisiae; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; D005656:Fungal Proteins; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C577587:mfr1 protein, S pombe; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; D008025:Ligases