ATP is required for the release of the anaphasepromoting complex/cyclosome from inhibition by the mitotic checkpoint

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 12; pp. 5351 - 5356
• Main Authors: Miniowitz-Shemtov, Shirly, Teichner, Adar, Sitry-Shevah, Danielle, Hershko, Avram
• Format: Journal Article
• Language: English
• Published: National Academy of Sciences 23.03.2010
• Subjects: Antibodies; Cyclins; Hydrolysis; Immunoprecipitation; Ligation; Mitotic spindle apparatus; Phosphorylation; Proteins; Rock cleavage; Ubiquitins
• ISSN: 0027-8424; 1091-6490

The mitotic (or spindle assembly) checkpoint system ensures accurate segregation of chromosomes by delaying anaphase until all chromosomes are correctly attached to the mitotic spindle. This system acts by inhibiting the activity of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase to target securin for degradation. APC/C is inhibited by a mitotic checkpoint complex (MCC) composed of BubR1, Bub3, Mad2, and Cdc20. The molecular mechanisms of the inactivation of the mitotic checkpoint, including the release of APC/C from inhibition, remain obscure. It has been reported that polyubiquitylation by the APC/C is required for the inactivation of the mitotic checkpoint [Reddy SK, Rape M, Margansky WA, Kirschner MW (2007) Nature, 446:921–924]. We confirmed the involvement of polyubiquitylation, but found that another process, which requires ATP cleavage at the β—γ position (as opposed to α—β bond scission involved in ubiquitylation), is essential for the release of APC/C from checkpoint inhibition. ATP (β—γ) cleavage is required both for the dissociation of MCC components from APC/C and for the disassembly of free MCC, whereas polyubiquitylation is involved only in the former process. We find that the requirement for ATP (β—γ) cleavage is not due to the involvement of the 26S proteasome and that the phenomena observed are not due to sustained activity of protein kinase Cdk1/cyclin B, caused by inhibition of the degradation of cyclin B. Thus, some other energy-consuming process is needed for the inactivation of the mitotic checkpoint.