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Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
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A high-sensitivity phospho-switch triggered by Cdk1 governs chromosome morphogenesis during cell division
Xavier Robellet1, Yogitha Thattikota1, Fang Wang1
1Institute for Research in Immunology and Cancer (IRIC), Département de Pathologie et Biologie Cellulaire, Université de Montréal, Montréal, Quebec H3C 3J7, Canada;
Genes & Development
|February 19, 2015
Summary
Researchers identified the core mechanism driving chromosome assembly during early mitosis. The sensitivity of chromosome condensation machinery to Cdk1 kinase activity, regulated by Smc4 protein phosphorylation, is key for chromatin compaction.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Chromosome morphogenesis initiates mitosis in eukaryotic cells.
- The trigger for global chromosome assembly remains largely unknown.
- Understanding chromatin compaction is crucial for cell division.
Purpose of the Study:
- To identify the core mechanism responsible for chromosome morphogenesis in early mitosis.
- To elucidate how chromatin compaction is regulated at mitotic entry.
- To investigate the role of Cdk1 kinase activity and Smc4 protein in chromosome assembly.
Main Methods:
- Investigated the sensitivity of chromosome condensation machinery to Cdk1 kinase activity.
- Analyzed the multisite phosphorylation of the Smc4 protein.
- Studied the effects of abrogating or reducing Smc4 phosphorylation on chromosome segregation.
Main Results:
- The unique sensitivity to Cdk1 kinase activity drives chromatin compaction at mitotic entry.
- Multisite phosphorylation of Smc4 integrates Cdk1 activation with condensation machinery binding.
- Abrogating Smc4 phosphorylation causes chromosome segregation defects and lethality.
- Reduced Smc4 phosphorylation reveals a novel "intertwist configuration" chromatin state.
Conclusions:
- Identified the mechanistic basis of chromosome morphogenesis in early mitosis.
- Distinct chromatin compaction states are established by specific Cdk1 kinase activity thresholds.
- Smc4 phosphorylation acts as a critical sensor for mitotic chromatin condensation.
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