title: Lack of the Glc7 phosphatase regulatory subunit Ypi1 activates the morphogenetic checkpoint.
abstract: Ypi1 is an essential regulator of the Saccharomyces cerevisiae Glc7 protein phosphatase. Although lack of Ypi1 results in a dramatic blockage in the G2/M cell cycle transition, with abnormally shaped large buds and short spindles, the molecular bases for this phenotype are still obscure. We report here that depletion of Ypi1 results in stabilization of the Pds1 securin, suggesting the activation of a G2/M checkpoint. Depletion of Ypi1 in cells deleted for MAD1/MAD2 or RAD9 still resulted in G2/M blockage, in spite that these cells lack key components of the spindle assembly and DNA damage checkpoints signaling, respectively. In contrast, deletion of SWE1, which encodes a protein kinase required for the morphogenesis checkpoint signaling, allowed passage through G2/M and recovery of normal cell morphology, although the cells did not proliferate. Depletion of Ypi1 caused stabilization of the Swe1 kinase, persistent phosphorylation of protein kinase Cdc28 at Y19, a landmark for morphogenesis checkpoint activation, and depletion of the Cdc11 septin, which explains the failure to form properly assembled septin rings at the bud necks. Deletion of SWE1 restored normal Cdc11 levels in the absence of Ypi1. These results demonstrate that Ypi1 plays an important role in the morphogenesis checkpoint, possibly by regulating Swe1.
authors: Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola 08193, Spain.
authors: Maribel
authors: M
authors: Marquina
authors: Ethel
authors: E
authors: Queralt
authors: Antonio
authors: A
authors: Casamayor
authors: Joaquín
authors: J
authors: Ariño
mesh_terms: D000483:Alleles; D059447:Cell Cycle Checkpoints; D002455:Cell Division; D004249:DNA Damage; D016195:G2 Phase; D017353:Gene Deletion; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency* / Q000378:metabolism; D008954:Models, Biological; D009024:Morphogenesis; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D054645:Protein Phosphatase 1 / Q000378:metabolism*; D055550:Protein Stability; D021122:Protein Subunits / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000201:enzymology / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D058112:Septins / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C480163:Ypi1 protein, S cerevisiae; C092048:GLC7 protein, S cerevisiae; D054645:Protein Phosphatase 1; D058112:Septins