title: Determination of human DNA polymerase utilization for the repair of a model ionizing radiation-induced DNA strand break lesion in a defined vector substrate.
abstract: Human DNA polymerase and DNA ligase utilization for the repair of a major class of ionizing radiation-induced DNA lesion [DNA single-strand breaks containing 3'-phosphoglycolate (3'-PG)] was examined using a novel, chemically defined vector substrate containing a single, site-specific 3'-PG single-strand break lesion. In addition, the major human AP endonuclease, HAP1 (also known as APE1, APEX, Ref-1), was tested to determine if it was involved in initiating repair of 3'-PG-containing single-strand break lesions. DNA polymerase beta was found to be the primary polymerase responsible for nucleotide incorporation at the lesion site following excision of the 3'-PG blocking group. However, DNA polymerase delta/straightepsilon was also capable of nucleotide incorporation at the lesion site following 3'-PG excision. In addition, repair reactions catalyzed by DNA polymerase beta were found to be most effective in the presence of DNA ligase III, while those catalyzed by DNA polymerase delta/straightepsilon appeared to be more effective in the presence of DNA ligase I. Also, it was demonstrated that the repair initiating 3'-PG excision reaction was not dependent upon HAP1 activity, as judged by inhibition of HAP1 with neutralizing HAP1-specific polyclonal antibody.
mesh_terms: D001483:Base Sequence; D019757:Carbon-Oxygen Lyases / Q000378:metabolism*; D002457:Cell Extracts; D004247:DNA / Q000235:genetics / Q000528:radiation effects; D004249:DNA Damage; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D043223:Deoxyribonuclease IV (Phage T4-Induced); D005822:Genetic Vectors; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D000075223:Poly-ADP-Ribose Binding Proteins; D013379:Substrate Specificity; D029867:Xenopus Proteins