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Updated: May 28, 2026
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Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae
Published on: September 11, 2022
The DNA damage checkpoint allows recombination between divergent DNA sequences in budding yeast
Carolyn M George1, Amy M Lyndaker, Eric Alani
1Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2073, United States.
DNA Repair
|October 8, 2011
Summary
The DNA damage response (DDR) and RAD9 gene regulate repair between divergent DNA sequences. Cell cycle arrest allows this repair, preventing harmful genome rearrangements.
Area of Science:
- Genetics
- Molecular Biology
- Cell Biology
Background:
- Homologous recombination repairs DNA breaks using homologous sequences.
- Recombination between divergent (homeologous) sequences can cause harmful genome rearrangements.
- Mismatch repair and helicases suppress homeologous recombination via heteroduplex rejection.
Purpose of the Study:
- To investigate the role of the DNA damage response (DDR), specifically the RAD9 gene, in regulating homeologous recombination.
- To determine if DDR influences the rejection of divergent DNA sequences during repair.
Main Methods:
- Utilized a DNA repair assay measuring single-strand annealing (SSA) of double-strand breaks (DSBs) using homeologous templates.
- Compared repair frequencies between RAD9 and rad9Δ strains.
- Induced G2 cell cycle delay using nocodazole in rad9Δ mutants.
Main Results:
- Repair of homeologous sequences, not identical ones, triggered a RAD9-dependent G2 cell cycle delay.
- Homeologous repair occurred more frequently in RAD9 strains than in rad9Δ strains.
- Inducing a G2 delay in rad9Δ mutants restored homeologous repair to wild-type levels.
Conclusions:
- Cell cycle arrest mediated by the Rad9-dependent DDR permits repair between divergent DNA sequences.
- This process prevents potentially deleterious genome rearrangements.
- Additional cellular mechanisms are crucial for suppressing recombination between divergent DNA sequences.
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