Repair of replication-dependent double-strand breaks differs between the leading and lagging strands.

Single-strand breaks (SSBs) are one of the most commonly occurring endogenous lesions with the potential to give rise to cytotoxic double-strand breaks (DSBs) during DNA replication. To investigate how replication-dependent DSBs are repaired, we employed Cas9 nickase (nCas9) to generate site- and strand-specific nicks in the budding yeast genome. We ...
found that nCas9-induced nicks are converted to mostly double-ended DSBs during S phase. Repair of replication-associated DSBs requires homologous recombination (HR) and is independent of classical non-homologous end joining. Consistent with a strong bias to repair these lesions using a sister-chromatid template, we observed minimal induction of inter-chromosomal HR by nCas9. In a genome-wide screen to identify factors necessary for the repair of replication-dependent DSBs, we recovered components of the replication-coupled nucleosome assembly (RCNA) pathway. Our findings suggest that the RCNA pathway is especially important to repair DSBs arising from nicks in the leading-strand template through acetylation of histone H3K56.
Mesh Terms:
CRISPR-Associated Protein 9, CRISPR-Cas Systems, DNA Breaks, Double-Stranded, DNA End-Joining Repair, DNA Repair, DNA Replication, DNA, Fungal, Histones, Homologous Recombination, Nucleosomes, Recombinational DNA Repair, S Phase, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Mol Cell
Date: Jan. 02, 2025
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