Phosphorylation of Cdc20 by Bub1 provides a catalytic mechanism for APC/C inhibition by the spindle checkpoint

Zhanyun Tang, Hongjun Shu, Dilhan Oncel, She Chen, Hongtao Yu

Research output: Contribution to journalArticlepeer-review

204 Scopus citations

Abstract

To ensure the fidelity of chromosome segregation, the spindle checkpoint blocks the ubiquitin ligase activity of APC/CCdc20 in response to a single chromatid not properly attached to the mitotic spindle. Here we show that HeLa cells depleted for Bub1 by RNA interference are defective in checkpoint signaling. Bub1 directly phosphorylates Cdc20 in vitro and inhibits the ubiquitin ligase activity of APC/CCdc20 catalytically. A Cdc20 mutant with all six Bub1 phosphorylation sites removed is refractory to Bub1-mediated phosphorylation and inhibition in vitro. Upon checkpoint activation, Bub1 itself is hyperphosphorylated and its kinase activity toward Cdc20 is stimulated. Ectopic expression of the nonphosphorylatable Cdc20 mutant allows HeLa cells to escape from mitosis in the presence of spindle damage. Therefore, Bub1-mediated phosphorylation of Cdc20 is required for proper checkpoint signaling. We speculate that inhibition of APC/CCdc20 by Bub1 in a catalytic fashion may partly account for the exquisite sensitivity of the spindle checkpoint.

Original languageEnglish (US)
Pages (from-to)387-397
Number of pages11
JournalMolecular cell
Volume16
Issue number3
DOIs
StatePublished - Nov 5 2004

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Phosphorylation of Cdc20 by Bub1 provides a catalytic mechanism for APC/C inhibition by the spindle checkpoint'. Together they form a unique fingerprint.

Cite this