Repair of abasic sites in DNA

Dianov, G. L., Sleeth, K. M., Dianova, I.I. and Allinson, S. L. (2003) Repair of abasic sites in DNA. Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis, 531 (1-2). pp. 157-163. ISSN 0027-5107 doi: 10.1016/j.mrfmmm.2003.09.003

Abstract/Summary

Repair of both normal and reduced AP sites is activated by AP endonuclease, which recognizes and cleaves a phosphodiester bond 5' to the AP site. For a short period of time an incised AP site is occupied by poly(ADP-ribose) polymerase and then DNA polymerase beta adds one nucleotide into the repair gap and simultaneously removes the 5'-sugar phosphate. Finally, the DNA ligase III/XRCC1 complex accomplishes repair by sealing disrupted DNA ends. However, long-patch BER pathway, which is involved in the removal of reduced abasic sites, requires further DNA synthesis resulting in strand displacement and the generation of a damage-containing flap that is later removed by the flap endonuclease. Strand-displacement DNA synthesis is accomplished by DNA polymerase delta/epsilon and DNA ligase I restores DNA integrity. DNA synthesis by DNA polymerase delta/epsilon is dependent on proliferating cell nuclear antigen, which also stimulates the DNA ligase I and flap endonuclease. These repair events are supported by multiple protein-protein interactions. (C) 2003 Elsevier B.V. All rights reserved.