Break-induced replication orchestrates resection-dependent template switching

Tianpeng Zhang, Yashpal Rawal, Haoyang Jiang, Youngho Kwon, Patrick Sung, Roger A. Greenberg

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Break-induced telomere synthesis (BITS) is a RAD51-independent form of break-induced replication that contributes to alternative lengthening of telomeres 1,2. This homology-directed repair mechanism utilizes a minimal replisome comprising proliferating cell nuclear antigen (PCNA) and DNA polymerase-δ to execute conservative DNA repair synthesis over many kilobases. How this long-tract homologous recombination repair synthesis responds to complex secondary DNA structures that elicit replication stress remains unclear 3–5. Moreover, whether the break-induced replisome orchestrates additional DNA repair events to ensure processivity is also unclear. Here we combine synchronous double-strand break induction with proteomics of isolated chromatin segments (PICh) to capture the telomeric DNA damage response proteome during BITS 1,6. This approach revealed a replication stress-dominated response, highlighted by repair synthesis-driven DNA damage tolerance signalling through RAD18-dependent PCNA ubiquitination. Furthermore, the SNM1A nuclease was identified as the major effector of ubiquitinated PCNA-dependent DNA damage tolerance. SNM1A recognizes the ubiquitin-modified break-induced replisome at damaged telomeres, and this directs its nuclease activity to promote resection. These findings show that break-induced replication orchestrates resection-dependent lesion bypass, with SNM1A nuclease activity serving as a critical effector of ubiquitinated PCNA-directed recombination in mammalian cells.

Original languageEnglish (US)
Pages (from-to)201-208
Number of pages8
Issue number7968
StatePublished - Jul 6 2023

ASJC Scopus subject areas

  • General


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