BubR1 acetylation at prometaphase is required for modulating APC/C activity and timing of mitosis

EMBO J. 2009 Jul 22;28(14):2077-89. doi: 10.1038/emboj.2009.123. Epub 2009 Apr 30.

Abstract

Regulation of BubR1 is central to the control of APC/C activity. We have found that BubR1 forms a complex with PCAF and is acetylated at lysine 250. Using mass spectrometry and acetylated BubR1-specific antibodies, we have confirmed that BubR1 acetylation occurs at prometaphase. Importantly, BubR1 acetylation was required for checkpoint function, through the inhibition of ubiquitin-dependent BubR1 degradation. BubR1 degradation began before the onset of anaphase. It was noted that the pre-anaphase degradation was regulated by BubR1 acetylation. Degradation of an acetylation-mimetic form, BubR1-K250Q, was inhibited and chromosome segregation in cells expressing BubR1-K250Q was markedly delayed. By contrast, the acetylation-deficient mutant, BubR1-K250R, was unstable, and mitosis was accelerated in BubR1-K250R-expressing cells. Furthermore, we found that APC/C-Cdc20 was responsible for BubR1 degradation during mitosis. On the basis of our collective results, we propose that the acetylation status of BubR1 is a molecular switch that converts BubR1 from an inhibitor to a substrate of the APC/C complex, thus providing an efficient way to modulate APC/C activity and mitotic timing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Amino Acid Sequence
  • Anaphase-Promoting Complex-Cyclosome
  • Animals
  • Cdc20 Proteins
  • Cell Cycle Proteins / metabolism
  • Genes, cdc
  • HeLa Cells
  • Humans
  • Kinetochores / metabolism
  • Mitosis*
  • Molecular Sequence Data
  • Protein Stability
  • Protein-Serine-Threonine Kinases / metabolism*
  • Sequence Alignment
  • Spindle Apparatus / metabolism*
  • Ubiquitin-Protein Ligase Complexes / metabolism
  • Ubiquitination
  • p300-CBP Transcription Factors / metabolism

Substances

  • Cdc20 Proteins
  • Cell Cycle Proteins
  • CDC20 protein, human
  • p300-CBP Transcription Factors
  • p300-CBP-associated factor
  • Ubiquitin-Protein Ligase Complexes
  • Anaphase-Promoting Complex-Cyclosome
  • BUB1 protein, human
  • Bub1 spindle checkpoint protein
  • Protein-Serine-Threonine Kinases