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Replication fork collapse and genome instability in a deoxycytidylate deaminase mutant
Arancha Sánchez1, Sushma Sharma, Sophie Rozenzhak
1Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, USA.
Molecular and Cellular Biology
|August 29, 2012
Summary
Fission yeast lacking dCMP deaminase (dcd1Δ) shows impaired DNA replication and repair, activating genome integrity checkpoints. This highlights dCMP deaminase
Area of Science:
- Molecular and Cellular Biology
- Genetics and Genomics
- DNA Replication and Repair
Background:
- Ribonucleotide reductase (RNR) and deoxycytidylate deaminase (dCMP deaminase) are crucial enzymes for maintaining deoxyribonucleoside triphosphate (dNTP) pools essential for DNA synthesis and repair.
- While RNR inhibition effects are well-studied, the consequences of dCMP deaminase deficiency on DNA metabolism and genome stability remain largely unexplored.
Purpose of the Study:
- To investigate the cellular and molecular consequences of deleting the dCMP deaminase gene (dcd1+) in the fission yeast Schizosaccharomyces pombe.
- To elucidate the role of dCMP deaminase in DNA replication, repair, and genome integrity maintenance.
Main Methods:
- Gene deletion of dcd1+ in Schizosaccharomyces pombe.
- Analysis of dNTP pool dynamics (dCTP, dTTP).
- Cell cycle progression analysis using DNA content profiling.
- Assessment of sensitivity to DNA-damaging agents.
- Investigation of genome integrity checkpoints (Rad3/ATR, Cds1/Chk2, Chk1).
- Analysis of proteins involved in replication fork recovery (Brc1, Mus81) and DNA repair (RPA, Rad52).
- Mutation rate analysis.
Main Results:
- Deletion of dcd1+ in fission yeast resulted in a significant increase in dCTP and a decrease in dTTP pools.
- dcd1Δ cells exhibited delayed cell cycle progression in early S phase and sensitivity to DNA-damaging agents, indicating impaired DNA replication and repair.
- dcd1 deficiency activated genome integrity checkpoints and required proteins involved in replication fork collapse recovery, such as Brc1 and Mus81.
- Increased nuclear foci of RPA and Rad52 were observed, alongside Brc1 suppressing spontaneous mutagenesis in dcd1Δ cells.
Conclusions:
- Fission yeast lacking dCMP deaminase experiences replication fork stalling and collapse, leading to increased DNA damage.
- The absence of dCMP deaminase burdens DNA damage and checkpoint responses, necessitating robust mechanisms to maintain genome integrity.
- These findings reveal a critical role for dCMP deaminase in ensuring accurate dNTP pools and supporting DNA replication fidelity.
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