title: BubR1 acetylation at prometaphase is required for modulating APC/C activity and timing of mitosis.
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.
authors.affiliation: Department of Biological Sciences and Institute of Molecular Biology and Genetics, College of Natural Sciences, Seoul National University, Seoul, Korea.
authors.forename: Eunhee
authors.initials: E
authors.lastname: Choi
authors.forename: Hyerim
authors.initials: H
authors.lastname: Choe
authors.forename: Jaewon
authors.initials: J
authors.lastname: Min
authors.forename: Ji Yoon
authors.initials: JY
authors.lastname: Choi
authors.forename: Jimi
authors.initials: J
authors.lastname: Kim
authors.forename: Hyunsook
authors.initials: H
authors.lastname: Lee
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D018816:Genes, cdc; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D008938:Mitosis; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D055550:Protein Stability; D016415:Sequence Alignment; D008941:Spindle Apparatus / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism; D054875:Ubiquitination; D050880:p300-CBP Transcription Factors / Q000378:metabolism; D000099224:p300-CBP-Associated Factor
chemical_list: D064173:Anaphase-Promoting Complex-Cyclosome; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D017346:Protein Serine-Threonine Kinases; D043743:Ubiquitin-Protein Ligase Complexes; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C577488:CDC20 protein, human; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein