title: Licensing of yeast centrosome duplication requires phosphoregulation of sfi1.
abstract: Duplication of centrosomes once per cell cycle is essential for bipolar spindle formation and genome maintenance and is controlled in part by cyclin-dependent kinases (Cdks). Our study identifies Sfi1, a conserved component of centrosomes, as the first Cdk substrate required to restrict centrosome duplication to once per cell cycle. We found that reducing Cdk1 phosphorylation by changing Sfi1 phosphorylation sites to nonphosphorylatable residues leads to defects in separation of duplicated spindle pole bodies (SPBs, yeast centrosomes) and to inappropriate SPB reduplication during mitosis. These cells also display defects in bipolar spindle assembly, chromosome segregation, and growth. Our findings lead to a model whereby phosphoregulation of Sfi1 by Cdk1 has the dual function of promoting SPB separation for spindle formation and preventing premature SPB duplication. In addition, we provide evidence that the protein phosphatase Cdc14 has the converse role of activating licensing, likely via dephosphorylation of Sfi1.
authors.affiliation: Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Avena
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
authors.forename: Shannon
authors.initials: S
authors.lastname: Burns
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
authors.forename: Zulin
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Ebmeier
authors.affiliation: Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America.
authors.forename: William M
authors.initials: WM
authors.lastname: Old
authors.affiliation: Stowers Institute for Medical Research, Kansas City, Missouri, United States of America; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States of America.
authors.forename: Sue L
authors.initials: SL
authors.lastname: Jaspersen
authors.affiliation: Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Winey
mesh_terms: D016203:CDC2 Protein Kinase / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics*; D018385:Centrosome; D058674:Chromosome Duplication / Q000235:genetics; D020090:Chromosome Segregation / Q000235:genetics; D008938:Mitosis / Q000235:genetics; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D008941:Spindle Apparatus / Q000235:genetics; D064048:Spindle Pole Bodies / Q000235:genetics*
chemical_list: C074860:CDC14 protein, S cerevisiae; D018797:Cell Cycle Proteins; D012097:Repressor Proteins; C121820:SFI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016203:CDC2 Protein Kinase; D017027:Protein Tyrosine Phosphatases