title: Repair of clustered DNA lesions. Sequence-specific inhibition of long-patch base excision repair be 8-oxoguanine.
abstract: Ionizing radiation induces clustered DNA damage where two or more lesions are located proximal to each other on the same or opposite DNA strands. It has been suggested that individual lesions within a cluster are removed sequentially and that the presence of a vicinal lesion(s) may affect the rate and fidelity of DNA repair. In this study, we addressed the question of how 8-oxoguanine located opposite to normal or reduced abasic sites would affect the repair of these sites by the base excision repair system. We have found that an 8-oxoguanine located opposite to an abasic site does not affect either the efficiency or fidelity of repair synthesis by DNA polymerase beta. In contrast, an 8-oxoguanine located one nucleotide 3'-downstream of the abasic site significantly reduces both strand displacement synthesis supported by DNA polymerase beta or delta and cleavage by flap endonuclease of the generated flap, thus inhibiting the long-patch base excision repair pathway.
authors.affiliation: Medical Research Council Radiation and Genome Stability Unit, Harwell, Oxfordshire OX11 0RD, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Budworth
authors.forename: Irina I
authors.initials: II
authors.lastname: Dianova
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Podust
authors.forename: Grigory L
authors.initials: GL
authors.lastname: Dianov
mesh_terms: D004249:DNA Damage; D019951:DNA Polymerase beta / Q000378:metabolism; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors
chemical_list: D011994:Recombinant Proteins; C024829:8-hydroxyguanine; D006147:Guanine; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase