Show Notes
Winterhalter et al., Rescuing the bacterial replisome at a nick requires recombinational repair and helicase reloading. Nat Commun ( - Cas9 nickases in Bacillus subtilis show that single-strand nicks in either template strand arrest DNA replication, create single-end double-strand breaks, and require homologous recombination plus PriA-dependent helicase reloading for replication restart. Key terms: DNA replication, recombinational repair, AddAB, PriA, SSB.
Study Highlights:
Site-specific nicks created with Cas9D10A block DNA synthesis downstream of the nick and induce RecA bundling in live cells. ChIP-qPCR shows helicase enrichment upstream of nicks and persistence downstream when the leading strand template is nicked, indicating helicase runs off the template for lagging-strand nicks but translocates onto dsDNA for leading-strand nicks. Genetic and marker frequency analyses identify AddAB helicase activity, RecFOR, RecA, RecG and PriA as essential for repair and PriA-dependent helicase reloading to resume replication. SSB C-terminal tail is required to recruit RecO and enable RecA loading, while AddAB nuclease activity is largely dispensable if helicase activity and an alternative nuclease provide ssDNA.
Conclusion:
B. subtilis repairs replisome inactivation at single-strand discontinuities via AddAB-mediated end-processing, RecFOR/RecA-mediated recombination, and PriA-dependent helicase reloading to restart replication
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Reference:
Winterhalter, C., Stratton, K.J., Fenyk, S. et al. Rescuing the bacterial replisome at a nick requires recombinational repair and helicase reloading. Nat Commun (2025). https://doi.org/10.1038/s41467-025-66550-w
License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/
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Episode Slug: replisome-nick-repair
