PCNA promotes processive DNA end resection by Exo1

Xiaoqing Chen, Sharad C. Paudyal, Re I. Chin, Zhongsheng You

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Exo1-mediated resection of DNA double-strand break ends generates 30 single-stranded DNA overhangs required for homology-based DNA repair and activation of the ATR-dependent checkpoint. Despite its critical importance in inducing the overall DNA damage response, the mechanisms and regulation of the Exo1 resection pathway remain incompletely understood. Here, we identify the ring-shaped DNA clamp PCNA as a new factor in the Exo1 resection pathway. Using mammalian cells, Xenopus nuclear extracts and purified proteins, we show that after DNA damage, PCNA loads onto double-strand breaks and promotes Exo1 damage association through direct interaction with Exo1. By tethering Exo1 to the DNA substrate, PCNA confers processivity to Exo1 in resection. This role of PCNA in DNA resection is analogous to its function in DNA replication where PCNA serves as a processivity co-factor for DNA polymerases.

Original languageEnglish
Pages (from-to)9325-9338
Number of pages14
JournalNucleic acids research
Issue number20
StatePublished - Nov 2013

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