title: Poly(ADP-ribose)-binding promotes Exo1 damage recruitment and suppresses its nuclease activities.
abstract: 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.
authors.affiliation: Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110, United States.
authors.forename: Abigael
authors.initials: A
authors.lastname: Cheruiyot
authors.affiliation: Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110, United States.
authors.forename: Sharad C
authors.initials: SC
authors.lastname: Paudyal
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, United States.
authors.forename: In-Kwon
authors.initials: IK
authors.lastname: Kim
authors.affiliation: Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110, United States.
authors.forename: Melanie
authors.initials: M
authors.lastname: Sparks
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, United States.
authors.forename: Tom
authors.initials: T
authors.lastname: Ellenberger
authors.affiliation: Department of Cancer Biology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77230, United States.
authors.forename: Helen
authors.initials: H
authors.lastname: Piwnica-Worms
authors.affiliation: Department of Cell Biology & Physiology, Washington University School of Medicine, St. Louis, MO 63110, United States. Electronic address: zyou@wustl.edu.
authors.forename: Zhongsheng
authors.initials: Z
authors.lastname: You
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000818:Animals; D002457:Cell Extracts; D002467:Cell Nucleus; D004249:DNA Damage; D004260:DNA Repair; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D045585:Flap Endonucleases / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D000071137:Poly (ADP-Ribose) Polymerase-1; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D014981:Xenopus
chemical_list: D048948:14-3-3 Proteins; D002457:Cell Extracts; D018809:Proliferating Cell Nuclear Antigen; D011064:Poly Adenosine Diphosphate Ribose; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D005090:Exodeoxyribonucleases; D045585:Flap Endonucleases; C028450:exodeoxyribonuclease I; D006026:Glycoside Hydrolases; C022407:poly ADP-ribose glycohydrolase
keywords: 14-3-3; DNA end resection; DNA replication; Exo1; PCNA; Poly(ADP-ribosyl)ation