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Disjunction of maternal and paternal centromeres during meiosis I requires crossing over between homologous chromatids, which creates chiasmata that hold homologs together. It also depends on a mechanism ensuring that maternal and paternal sister kinetochore pairs attach to oppositely oriented microtubules. Proteolytic cleavage of cohesin's Rec8 subunit by separase destroys cohesion between sister chromatid arms at anaphase I and thereby resolves chiasmata. The Spo12 and Slk19 proteins have been implicated in regulating meiosis I kinetochore orientation and/or in preventing cleavage of Rec8 at centromeres. We show here that the role of these proteins is instead to promote nucleolar segregation, including release of the Cdc14 phosphatase required for Cdk1 inactivation and disassembly of the anaphase I spindle. Separase is also required but surprisingly not its protease activity. It has two mechanistically different roles during meiosis I. Loss of the protease-independent function alone results in a second meiotic division occurring on anaphase I spindles in spo12delta and slk19delta mutants.

Type

Journal article

Journal

Dev Cell

Publication Date

05/2003

Volume

4

Pages

727 - 739

Keywords

Anaphase, Cell Cycle Proteins, Cell Nucleolus, Cyclin B, Cyclins, Down-Regulation, Endopeptidases, Fungal Proteins, In Situ Hybridization, Fluorescence, Meiosis, Microtubule-Associated Proteins, Nuclear Proteins, Protein Kinases, Protein Tyrosine Phosphatases, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Separase, Time Factors