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DNA repair mutants defining G2 checkpoint pathways in Schizosaccharomyces pombe
1MRC Cell Mutation Unit, Sussex University, Falmer, UK.
Abstract:
We have tested mutants corresponding to 20 DNA repair genes of the fission yeast Schizosaccharomyces pombe for their ability to arrest in G2 after DNA damage. Of the mutants tested, four are profoundly defective in this damage dependent G2 arrest. In addition, these four mutants are highly sensitive to a transient inhibition of DNA synthesis by hydroxyurea. This suggests that the pathway responsible for the recognition of DNA damage and the subsequent mitotic arrest, shares many functions with the mechanism that controls the dependency of mitosis on the completion of S phase. The phenotype of these checkpoint rad mutants in wee mutant backgrounds indicate that the G2 arrest response is mediated either through, or in parallel with, the activity of the cdc2 gene product.
Insights
Four DNA repair mutants of Schizosaccharomyces pombe are defective in G2 arrest after DNA damage, indicating shared pathways between DNA repair and cell cycle checkpoints.
Area of Science:
- Cell Biology
- Genetics
- Molecular Biology
Background:
- DNA damage triggers cell cycle checkpoints to prevent genomic instability.
- The G2/M checkpoint ensures proper DNA replication and repair before mitosis.
- Schizosaccharomyces pombe is a model organism for studying cell cycle regulation.
Purpose of the Study:
- To identify DNA repair genes involved in the G2/M DNA damage checkpoint in fission yeast.
- To investigate the relationship between DNA repair, S phase completion, and mitotic entry.
Main Methods:
- Screening of 20 DNA repair mutants in Schizosaccharomyces pombe.
- Assessing G2 arrest response following DNA damage induction.
- Evaluating sensitivity to hydroxyurea, an inhibitor of DNA synthesis.
Main Results:
- Four DNA repair mutants exhibited profound defects in DNA damage-induced G2 arrest.
- These mutants showed high sensitivity to hydroxyurea, indicating impaired S phase control.
- The G2 arrest pathway appears to involve or run parallel to the cdc2 gene product.
Conclusions:
- DNA repair pathways are crucial for the G2 DNA damage checkpoint.
- There is functional overlap between the DNA damage response and the S phase to mitosis control.
- The cdc2 gene product plays a role in mediating the G2 arrest response.