title: AP endonuclease and poly(ADP-ribose) polymerase-1 interact with the same base excision repair intermediate.
abstract: Base excision repair (BER) is a defense system that protects cells from deleterious effects secondary to modified or missing DNA bases. BER is known to involve apurinic/apyrimidinic endonuclease (APE) and DNA polymerase ss (ss-pol) among other enzymes, and recent studies have suggested that poly(ADP-ribose) polymerase-1 (PARP-1) also plays a role by virtue of its binding to BER intermediates. The main role of APE is cleavage of the DNA backbone at abasic sites, and the enzyme also can catalyze 3'- to 5'-exonuclease activity at the cleaved abasic site. Photocross-linking studies with mouse embryonic fibroblast (MEF) cell extracts described here indicated that APE and PARP-1 interact with the same APE-cleaved abasic site BER intermediate. The model BER intermediate used includes a synthetic abasic site sugar, i.e. tetrahydrofuran (THF), in place of the natural deoxyribose. APE cross-linked efficiently with this intermediate, but not with a molecule lacking the 5'-THF phosphate group, and the same property was demonstrated for PARP-1. The addition of purified APE to the MEF extract reduced the amount of PARP-1 cross-linked to the BER intermediate, suggesting that APE can compete with PARP-1. APE and PARP-1 were antagonists of each other in in vitro BER related reactions on this model BER intermediate. These results suggest that PARP-1 and APE can interact with the same BER intermediate and that competition between these two proteins may influence their respective BER related functions.
authors.affiliation: Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 11 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Cistulli
authors.forename: Olga I
authors.initials: OI
authors.lastname: Lavrik
authors.forename: Rajendra
authors.initials: R
authors.lastname: Prasad
authors.forename: Esther
authors.initials: E
authors.lastname: Hou
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002478:Cells, Cultured; D003432:Cross-Linking Reagents; D019951:DNA Polymerase beta / Q000235:genetics / Q000502:physiology; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D005663:Furans / Q000378:metabolism*; D006720:Homozygote; D051379:Mice; D018345:Mice, Knockout / Q000196:embryology; D019920:Photoaffinity Labels / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D005663:Furans; D019920:Photoaffinity Labels; C018674:tetrahydrofuran; D011065:Poly(ADP-ribose) Polymerases; D019951:DNA Polymerase beta; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase