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Different Functionality of Cdc20 Binding Sites within the Mitotic Checkpoint Complex.
Katharina Sewart1, Silke Hauf1
1Department of Biological Sciences and Biocomplexity Institute, Virginia Tech, 1015 Life Science Circle, Blacksburg, VA 24061, USA.
Current Biology : CB
|April 4, 2017
Summary
The mitotic checkpoint prevents errors during cell division. This study shows how the mitotic checkpoint complex (MCC) binds Cdc20, ensuring proper chromosome segregation and revealing new insights into cancer cell biology.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The mitotic checkpoint is crucial for preventing chromosome missegregation, a hallmark of cancer.
- The mitotic checkpoint complex (MCC) inhibits the anaphase-promoting complex/cyclosome (APC/C) by targeting its activator, Cdc20.
- Recent studies suggest the MCC binds two Cdc20 molecules via distinct mechanisms.
Purpose of the Study:
- To investigate the in vivo functionality of different Cdc20 binding sites within the MCC.
- To elucidate the role of the Mad3 ABBA-KEN2-ABBA motif in MCC function.
- To understand the interplay between MCC, Cdc20, and APC/C in fission yeast.
Main Methods:
- Utilized fission yeast as a model organism.
- Performed in vivo functional assays to assess checkpoint activity.
- Investigated the role of specific protein motifs and subunits through genetic manipulation (e.g., deletion of Apc15).
Main Results:
- At low Cdc20 concentrations, binding to the core MCC is sufficient for checkpoint function.
- The Mad3 ABBA-KEN2-ABBA motif is essential for secondary Cdc20 binding, MCC-APC/C interaction, and MCC disassembly.
- Deletion of Apc15 phenocopies mutations in the Mad3 motif, indicating a shared function in MCC regulation.
Conclusions:
- Provides in vivo validation for structural models of MCC-Cdc20 interactions.
- Dissects three key mechanisms of Cdc20 inhibition by the MCC.
- Highlights the conserved role of Mad3 and Apc15 in regulating MCC activity and APC/C binding.