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CDK phosphorylation of Drc1 regulates DNA replication in fission yeast
Eishi Noguchi1, Paul Shanahan, Chiaki Noguchi
1Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Abstract:
Cyclin-dependent kinases (CDKs) are absolutely required for DNA replication in eukaryotic cells. CDKs are thought to activate one or more replication factors, but the identities of these proteins are unknown. Here we describe fission yeast Drc1, a protein required for DNA replication that is phosphorylated by Cdc2. Drc1 depletion leads to catastrophic mitotic divisions with incompletely replicated DNA, indicating that Drc1 is required for DNA synthesis and S-M replication checkpoint control. Drc1 associates with Cdc2 and is phosphorylated at the onset of S phase when Cdc2 is activated. Mutant Drc1 that lacks CDK phosphorylation sites is nonfunctional and fails to interact with Cut5 replication factor. These data suggest that Cdc2 promotes DNA replication by phosphorylating Drc1 and regulating its association with Cut5.
Insights
Fission yeast Drc1 protein is essential for DNA replication and cell cycle control. Phosphorylation of Drc1 by Cdc2 is crucial for its function and interaction with replication factors, ensuring complete DNA synthesis.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cyclin-dependent kinases (CDKs) are vital for DNA replication in eukaryotic cells.
- The specific replication factors activated by CDKs remain largely unidentified.
Purpose of the Study:
- To identify and characterize a novel protein, Drc1, involved in DNA replication in fission yeast.
- To elucidate the role of CDK-mediated phosphorylation in regulating DNA replication factors.
Main Methods:
- Depletion of Drc1 in fission yeast.
- Analysis of DNA replication and cell division.
- Co-immunoprecipitation to study protein interactions.
- Site-directed mutagenesis to investigate phosphorylation sites.
Main Results:
- Drc1 is required for DNA synthesis and S-M replication checkpoint control.
- Drc1 is phosphorylated by Cdc2 (a CDK) at the start of S phase.
- Mutant Drc1 lacking CDK phosphorylation sites is nonfunctional and does not interact with the Cut5 replication factor.
Conclusions:
- Cdc2 promotes DNA replication by phosphorylating Drc1.
- Phosphorylation regulates Drc1's association with the replication factor Cut5, highlighting a key mechanism in DNA replication control.