title: p31comet Promotes disassembly of the mitotic checkpoint complex in an ATP-dependent process.
abstract: Accurate segregation of chromosomes in mitosis is ensured by a surveillance mechanism called the mitotic (or spindle assembly) checkpoint. It prevents sister chromatid separation until all chromosomes are correctly attached to the mitotic spindle through their kinetochores. The checkpoint acts by inhibiting the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase that targets for degradation securin, an inhibitor of anaphase initiation. The activity of APC/C is inhibited by a mitotic checkpoint complex (MCC), composed of the APC/C activator Cdc20 bound to the checkpoint proteins MAD2, BubR1, and Bub3. When all kinetochores acquire bipolar attachment the checkpoint is inactivated, but the mechanisms of checkpoint inactivation are not understood. We have previously observed that hydrolyzable ATP is required for exit from checkpoint-arrested state. In this investigation we examined the possibility that ATP hydrolysis in exit from checkpoint is linked to the action of the Mad2-binding protein p31(comet) in this process. It is known that p31(comet) prevents the formation of a Mad2 dimer that it thought to be important for turning on the mitotic checkpoint. This explains how p31(comet) blocks the activation of the checkpoint but not how it promotes its inactivation. Using extracts from checkpoint-arrested cells and MCC isolated from such extracts, we now show that p31(comet) causes the disassembly of MCC and that this process requires β,γ-hydrolyzable ATP. Although p31(comet) binds to Mad2, it promotes the dissociation of Cdc20 from BubR1 in MCC.
authors.affiliation: Unit of Biochemistry, The Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel.
authors.forename: Adar
authors.initials: A
authors.lastname: Teichner
authors.forename: Esther
authors.initials: E
authors.lastname: Eytan
authors.forename: Danielle
authors.initials: D
authors.lastname: Sitry-Shevah
authors.forename: Shirly
authors.initials: S
authors.lastname: Miniowitz-Shemtov
authors.forename: Elena
authors.initials: E
authors.lastname: Dumin
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gromis
authors.forename: Avram
authors.initials: A
authors.lastname: Hershko
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D064173:Anaphase-Promoting Complex-Cyclosome; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D064246:Mad2 Proteins; D008938:Mitosis; D009687:Nuclear Proteins / Q000502:physiology*; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000037:antagonists & inhibitors*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C489444:BUB3 protein, human; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; C470309:MAD2L1BP protein, human; C120552:MAD2L2 protein, human; D064246:Mad2 Proteins; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D011506:Proteins; C577488:CDC20 protein, human; D000255:Adenosine Triphosphate; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases