Direct binding between BubR1 and B56-PP2A phosphatase complexes regulate mitotic progression

J Cell Sci. 2013 Mar 1;126(Pt 5):1086-92. doi: 10.1242/jcs.122481. Epub 2013 Jan 23.

Abstract

BubR1 is a central component of the spindle assembly checkpoint that inhibits progression into anaphase in response to improper kinetochore-microtubule interactions. In addition, BubR1 also helps stabilize kinetochore-microtubule interactions by counteracting the Aurora B kinase but the mechanism behind this is not clear. Here we show that BubR1 directly binds to the B56 family of protein phosphatase 2A (PP2A) regulatory subunits through a conserved motif that is phosphorylated by cyclin-dependent kinase 1 (Cdk1) and polo-like kinase 1 (Plk1). Two highly conserved hydrophobic residues surrounding the serine 670 Cdk1 phosphorylation site are required for B56 binding. Mutation of these residues prevents the establishment of a proper metaphase plate and delays cells in mitosis. Furthermore, we show that phosphorylation of serines 670 and 676 stimulates the binding of B56 to BubR1 and that BubR1 targets a pool of B56 to kinetochores. Our data suggest that BubR1 counteracts Aurora B kinase activity at improperly attached kinetochores by recruiting B56-PP2A phosphatase complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CDC2 Protein Kinase / metabolism
  • Cell Cycle Proteins / metabolism
  • Chromatography, Gel
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Microscopy, Fluorescence
  • Mitosis / genetics
  • Mitosis / physiology*
  • Phosphorylation
  • Protein Binding
  • Protein Phosphatase 2 / metabolism*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism
  • Two-Hybrid System Techniques

Substances

  • Cell Cycle Proteins
  • PPP2R5A protein, human
  • Proto-Oncogene Proteins
  • BUB1 protein, human
  • Bub1 spindle checkpoint protein
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1
  • CDC2 Protein Kinase
  • Protein Phosphatase 2