title: Cdk1 phosphorylation of BubR1 controls spindle checkpoint arrest and Plk1-mediated formation of the 3F3/2 epitope.
abstract: Accurate chromosome segregation is controlled by the spindle checkpoint, which senses kinetochore- microtubule attachments and tension across sister kinetochores. An important step in the tension-signaling pathway involves the phosphorylation of an unknown protein by polo-like kinase 1/Xenopus laevis polo-like kinase 1 (Plx1) on kinetochores lacking tension to generate the 3F3/2 phosphoepitope. We report here that the checkpoint protein BubR1 interacts with Plx1 and that phosphorylation of BubR1 by Plx1 generates the 3F3/2 epitope. Formation of the BubR1 3F3/2 epitope by Plx1 requires a prior phosphorylation of BubR1 on Thr 605 by cyclin-dependant kinase 1 (Cdk1). This priming phosphorylation of BubR1 by Cdk1 is required for checkpoint-mediated mitotic arrest and for recruitment of Plx1 and the checkpoint protein Mad2 to unattached kinetochores. Biochemically, formation of the 3F3/2 phosphoepitope by Cdk1 and Plx1 greatly enhances the kinase activity of BubR1. Thus, Cdk1-mediated phosphorylation of BubR1 controls checkpoint arrest and promotes the formation of the kinetochore 3F3/2 epitope.
authors.affiliation: Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.
authors.forename: Oi Kwan
authors.initials: OK
authors.lastname: Wong
authors.forename: Guowei
authors.initials: G
authors.lastname: Fang
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D000939:Epitopes / Q000096:biosynthesis*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D008941:Spindle Apparatus / Q000502:physiology*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014982:Xenopus laevis; D000097869:Polo-Like Kinase 1
chemical_list: D016203:CDC2 Protein Kinase; D018797:Cell Cycle Proteins; D000939:Epitopes; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D029867:Xenopus Proteins; D000097869:Polo-Like Kinase 1; C524954:BUB1B protein, Xenopus; C101085:Plk1 protein, Xenopus