Poly(ADP-ribose)-binding promotes Exo1 damage recruitment and suppresses its nuclease activities

DNA Repair (Amst). 2015 Nov;35:106-15. doi: 10.1016/j.dnarep.2015.09.021. Epub 2015 Sep 30.


Exonuclease 1 (Exo1) has important roles in DNA metabolic transactions that are essential for genome maintenance, telomere regulation and cancer suppression. However, the mechanisms for regulating Exo1 activity in these processes remain incompletely understood. Here, we report that Exo1 activity is regulated by a direct interaction with poly(ADP-ribose) (PAR), a prominent posttranslational modification at the sites of DNA damage. This PAR-binding activity promotes the early recruitment of Exo1 to sites of DNA damage, where it is retained through an interaction with PCNA, which interacts with the C-terminus of Exo1. The effects of both PAR and PCNA on Exo1 damage association are antagonized by the 14-3-3 adaptor proteins, which interact with the central domain of Exo1. Although PAR binding inhibits both the exonuclease activity and the 5' flap endonuclease activity of purified Exo1, the pharmacological blockade of PAR synthesis does not overtly affect DNA double-strand break end resection in a cell free Xenopus egg extract. Thus, the counteracting effects of PAR on Exo1 recruitment and enzymatic activity may enable appropriate resection of DNA ends while preventing unscheduled or improper processing of DNA breaks in cells.

Keywords: 14-3-3; DNA end resection; DNA replication; Exo1; PCNA; Poly(ADP-ribosyl)ation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / metabolism
  • Animals
  • Cell Extracts
  • Cell Nucleus
  • DNA Damage*
  • DNA Repair*
  • Exodeoxyribonucleases / metabolism*
  • Flap Endonucleases / metabolism*
  • Glycoside Hydrolases / metabolism
  • HEK293 Cells
  • Humans
  • Poly (ADP-Ribose) Polymerase-1
  • Poly Adenosine Diphosphate Ribose / metabolism*
  • Poly(ADP-ribose) Polymerases
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Protein Processing, Post-Translational
  • Xenopus


  • 14-3-3 Proteins
  • Cell Extracts
  • Proliferating Cell Nuclear Antigen
  • Poly Adenosine Diphosphate Ribose
  • PARP1 protein, human
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases
  • Exodeoxyribonucleases
  • Flap Endonucleases
  • exodeoxyribonuclease I
  • Glycoside Hydrolases
  • poly ADP-ribose glycohydrolase