Minimal Resection Takes Place during Break-Induced Replication Repair of Collapsed Replication Forks and Is Controlled by Strand Invasion

• Published in: Cell reports (Cambridge) Vol. 26; no. 4; pp. 836 - 844.e3
• Main Authors: Jakobsen, Kristoffer P., Nielsen, Kirstine O., Løvschal, Katrine V., Rødgaard, Morten, Andersen, Anni H., Bjergbæk, Lotte
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 22-01-2019
• Subjects: break-induced replication; DNA Breaks, Double-Stranded; DNA Breaks, Single-Stranded; DNA Replication; DNA Topoisomerases, Type I - genetics; DNA Topoisomerases, Type I - metabolism; DNA, Fungal - biosynthesis; DNA, Fungal - genetics; double-strand break repair; Hydroxyurea - pharmacology; resection; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; topoisomerase-generated damage; resection; double-strand break repair; topoisomerase-generated damage; break-induced replication
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2018.12.108

A natural and frequently occurring replication problem is generated by the action of topoisomerase I (Top1). Trapping of Top1 in a cleavage complex on the DNA generates a protein-linked DNA nick (PDN), which upon DNA replication can be transformed into a one-ended double-strand break (DSB). Break-induced replication (BIR) has been recognized as a critical repair mechanism of one-ended DSBs. Here, we have investigated resection at a one-ended DSB formed exclusively during replication due to Top1-mimicking damage. We show that resection is minimal, and only when strand invasion is abolished is extensive resection detected. When DNA synthesis is slowed by hydroxyurea treatment, extended resection is not observed, which suggests that strand invasion and/or heteroduplex formation restrains resection. Our results demonstrate that the BIR pathway acting during S phase is tailored to prevent hazardous effects of naturally and frequently occurring DNA breaks such as Top1-generated PDNs.
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•Repair of collapsed forks at Top1-generated damage generates minimal ssDNA•DNA synthesis during repair does not influence resection length•Absence of Rad52 or Rad54 leads to extensive resection at collapsed forks•Strand invasion and stable synaptic structure affect resection length
Jakobsen et al. examine single-stranded DNA formed during repair of a double-strand break. They show that resection is minimal at a double-strand break formed exclusively due to replication fork collapse, when normal repair is allowed.