Synergistic blockade of mitotic exit by two chemical inhibitors of the APC/C

Nature. 2014 Oct 30;514(7524):646-9. doi: 10.1038/nature13660. Epub 2014 Aug 24.


Protein machines are multi-subunit protein complexes that orchestrate highly regulated biochemical tasks. An example is the anaphase-promoting complex/cyclosome (APC/C), a 13-subunit ubiquitin ligase that initiates the metaphase-anaphase transition and mitotic exit by targeting proteins such as securin and cyclin B1 for ubiquitin-dependent destruction by the proteasome. Because blocking mitotic exit is an effective approach for inducing tumour cell death, the APC/C represents a potential novel target for cancer therapy. APC/C activation in mitosis requires binding of Cdc20 (ref. 5), which forms a co-receptor with the APC/C to recognize substrates containing a destruction box (D-box). Here we demonstrate that we can synergistically inhibit APC/C-dependent proteolysis and mitotic exit by simultaneously disrupting two protein-protein interactions within the APC/C-Cdc20-substrate ternary complex. We identify a small molecule, called apcin (APC inhibitor), which binds to Cdc20 and competitively inhibits the ubiquitylation of D-box-containing substrates. Analysis of the crystal structure of the apcin-Cdc20 complex suggests that apcin occupies the D-box-binding pocket on the side face of the WD40-domain. The ability of apcin to block mitotic exit is synergistically amplified by co-addition of tosyl-l-arginine methyl ester, a small molecule that blocks the APC/C-Cdc20 interaction. This work suggests that simultaneous disruption of multiple, weak protein-protein interactions is an effective approach for inactivating a protein machine.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anaphase-Promoting Complex-Cyclosome / chemistry*
  • Anaphase-Promoting Complex-Cyclosome / metabolism*
  • Binding Sites / drug effects
  • Carbamates / pharmacology*
  • Cdc20 Proteins / chemistry
  • Cdc20 Proteins / metabolism
  • Cell Death / drug effects
  • Crystallography, X-Ray
  • Diamines / pharmacology*
  • Drug Synergism
  • Mitosis / drug effects*
  • Protein Binding / drug effects
  • Proteolysis / drug effects
  • Tosylarginine Methyl Ester / pharmacology*
  • Ubiquitination / drug effects


  • Carbamates
  • Cdc20 Proteins
  • Diamines
  • apcin
  • Tosylarginine Methyl Ester
  • Anaphase-Promoting Complex-Cyclosome

Associated data

  • PDB/4N14