title: Meiotic nuclear divisions in budding yeast require PP2A(Cdc55)-mediated antagonism of Net1 phosphorylation by Cdk.
abstract: During meiosis, one round of deoxyribonucleic acid replication is followed by two rounds of nuclear division. In Saccharomyces cerevisiae, activation of the Cdc14 early anaphase release (FEAR) network is required for exit from meiosis I but does not lead to the activation of origins of replication. The precise mechanism of how FEAR regulates meiosis is not understood. In this paper, we report that premature activation of FEAR during meiosis caused by loss of protein phosphatase PP2A(Cdc55) activity blocks bipolar spindle assembly and nuclear divisions. In cdc55 meiotic null (cdc55-mn) cells, the cyclin-dependent kinase (Cdk)-counteracting phosphatase Cdc14 was released prematurely from the nucleolus concomitant with hyperphosphorylation of its nucleolar anchor protein Net1. Crucially, a mutant form of Net1 that lacks six Cdk phosphorylation sites rescued the meiotic defect of cdc55-mn cells. Expression of a dominant mutant allele of CDC14 mimicked the cdc55-mn phenotype. We propose that phosphoregulation of Net1 by PP2A(Cdc55) is essential for preventing precocious exit from meiosis I.
authors.affiliation: University of Warwick, Coventry CV4 7AL, England, UK.
authors.forename: Gary W
authors.initials: GW
authors.lastname: Kerr
authors.forename: Sourav
authors.initials: S
authors.lastname: Sarkar
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Tibbles
authors.forename: Mark
authors.initials: M
authors.lastname: Petronczki
authors.forename: Jonathan B A
authors.initials: JB
authors.lastname: Millar
authors.forename: Prakash
authors.initials: P
authors.lastname: Arumugam
mesh_terms: D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D018844:Cyclin-Dependent Kinases / Q000378:metabolism / Q000502:physiology*; D008540:Meiosis / Q000502:physiology*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000502:physiology*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
chemical_list: C074860:CDC14 protein, S cerevisiae; C071246:CDC55 protein, S cerevisiae; D018797:Cell Cycle Proteins; C119300:Net1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D018844:Cyclin-Dependent Kinases; D054648:Protein Phosphatase 2; D017027:Protein Tyrosine Phosphatases