Human base excision repair enzymes apurinic/apyrimidinic endonuclease1 (APE1), DNA polymerase β and poly(ADP-ribose) polymerase 1: interplay between strand-displacement DNA synthesis and proofreading exonuclease activity

We examined interactions between base excision repair (BER) DNA intermediates and purified human BER enzymes, DNA polymerase β (pol β), apurinic/apyrimidinic endonuclease (APE1) and poly(ADP-ribose) polymerase-1 (PARP-1). Studies under steady-state conditions with purified BER enzymes and BER substr...

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Bibliographic Details
Published in:Nucleic acids research 2005, Vol.33 (4), p.1222-1229
Main Authors: Sukhanova, Maria V., Khodyreva, Svetlana N., Lebedeva, Natalia A., Prasad, Rajendra, Wilson, Samuel H., Lavrik, Olga I.
Format: Article
Language:English
Subjects:
Base Pair Mismatch
DNA - biosynthesis
DNA Polymerase beta - metabolism
DNA Repair
DNA-(Apurinic or Apyrimidinic Site) Lyase - metabolism
Exodeoxyribonucleases - metabolism
Humans
Poly(ADP-ribose) Polymerases - metabolism
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Summary:We examined interactions between base excision repair (BER) DNA intermediates and purified human BER enzymes, DNA polymerase β (pol β), apurinic/apyrimidinic endonuclease (APE1) and poly(ADP-ribose) polymerase-1 (PARP-1). Studies under steady-state conditions with purified BER enzymes and BER substrates have already demonstrated interplay between these BER enzymes that is sensitive to the respective concentrations of each enzyme. Therefore, in this study, using conditions of enzyme excess over substrate DNA, we further examine the question of interplay between BER enzymes on BER intermediates. The results reveal several important differences compared with data obtained using steady-state assays. Excess PARP-1 antagonizes the action of pol β, producing a complete block of long patch BER strand-displacement DNA synthesis. Surprisingly, an excess of APE1 stimulates strand-displacement DNA synthesis by pol β, but this effect is blocked by PARP-1. The APE1 exonuclease function appears to be modulated by the other BER proteins. Excess APE1 over pol β may allow APE1 to perform both exonuclease function and stimulation of strand-displacement DNA synthesis by pol β. This enables pol β to mediate long patch sub-pathway. These results indicate that differences in the stoichiometry of BER enzymes may regulate BER.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gki266