AP endonuclease and poly(ADP-ribose) polymerase-1 interact with the same base excision repair intermediate

DNA Repair (Amst). 2004 Jun 3;3(6):581-91. doi: 10.1016/j.dnarep.2003.09.012.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding, Competitive
  • Cells, Cultured
  • Cross-Linking Reagents
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / physiology
  • DNA Repair*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / metabolism*
  • Fibroblasts / cytology
  • Fibroblasts / enzymology*
  • Furans / metabolism*
  • Homozygote
  • Mice
  • Mice, Knockout / embryology
  • Photoaffinity Labels / metabolism*
  • Poly(ADP-ribose) Polymerases / metabolism*


  • Cross-Linking Reagents
  • Furans
  • Photoaffinity Labels
  • tetrahydrofuran
  • Poly(ADP-ribose) Polymerases
  • DNA Polymerase beta
  • DNA-(Apurinic or Apyrimidinic Site) Lyase