Endonuclease EEPD1 Is a gatekeeper for repair of stressed replication forks

Hyun Suk Kim, Jac A. Nickoloff, Yuehan Wu, Elizabeth A. Williamson, Gurjit Singh Sidhu, Brian L. Reinert, Aruna S. Jaiswal, Gayathri Srinivasan, Bhavita Patel, Kimi Kong, Sandeep Burma, Suk Hee Lee, Robert A. Hromas

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Replication is not as continuous as once thought, with DNA damage frequently stalling replication forks. Aberrant repair of stressed replication forks can result in cell death or genome instability and resulting transformation to malignancy. Stressed replication forks are most commonly repaired via homologous recombination (HR), which begins with 5′ end resection, mediated by exonuclease complexes, one of which contains Exo1.However, Exo1 requires free 5′-DNA ends upon which to act, and these are not commonly present in non-reversed stalled replication forks. To generate a free 5′ end, stalled replication forks must therefore be cleaved. Although several candidate endonucleases have been implicated in cleavage of stalled replication forks to permit end resection, the identity of such an endonuclease remains elusive. Here we show that the 5′-endonuclease EEPD1 cleaves replication forks at the junction between the lagging parental strand and the unreplicated DNA parental double strands. This cleavage creates the structure that Exo1 requires for 5′ end resection and HR initiation. We observed that EEPD1 and Exo1 interact constitutively, and Exo1 repairs stalled replication forks poorly without EEPD1. Thus, EEPD1 performs a gatekeeper function for replication fork repair by mediating the fork cleavage that permits initiation of HR-mediated repair and restart of stressed forks.

Original languageEnglish (US)
Pages (from-to)2795-2804
Number of pages10
JournalJournal of Biological Chemistry
Issue number7
StatePublished - Feb 17 2017
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry
  • Cell Biology


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