title: Cdc55 coordinates spindle assembly and chromosome disjunction during meiosis.
abstract: During meiosis, two consecutive nuclear divisions follow a single round of deoxyribonucleic acid replication. In meiosis I, homologues are segregated, whereas in meiosis II, sister chromatids are segregated. This requires that the sequential assembly and dissolution of specialized chromosomal factors are coordinated with two rounds of spindle assembly and disassembly. How these events are coupled is unknown. In this paper, we show, in budding yeast, that the protein phosphatase 2A regulatory subunit Cdc55 couples the loss of linkages between chromosomes with nuclear division by restraining two other phosphatases, Cdc14 and PP2A(Rts1). Cdc55 maintains Cdc14 sequestration in the nucleolus during early meiosis, and this is essential for the assembly of the meiosis I spindle but not for chromosomes to separate. Cdc55 also limits the formation of PP2A holocomplexes containing the alternative regulatory subunit Rts1, which is crucial for the timely dissolution of sister chromatid cohesion. Therefore, Cdc55 orders passage through the meiotic divisions by ensuring a balance of phosphatases.
authors.affiliation: Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.
authors.forename: Farid
authors.initials: F
authors.lastname: Bizzari
authors.forename: Adele L
authors.initials: AL
authors.lastname: Marston
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D020090:Chromosome Segregation; D015825:Chromosomes, Fungal / Q000378:metabolism*; D019926:Cyclin B / Q000378:metabolism; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018386:Kinetochores / Q000378:metabolism / Q000648:ultrastructure; D008540:Meiosis / Q000235:genetics*; D054648:Protein Phosphatase 2 / Q000378:metabolism / Q000502:physiology*; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000378:metabolism / Q000502:physiology; D004718:Saccharomycetales / Q000166:cytology / Q000235:genetics*; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism*; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D019926:Cyclin B; D005656:Fungal Proteins; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases; D000097722:Cohesins