Formation of novel C1-oxidised abasic sites in alkylperoxyl radical-damaged plasmid DNA.
We have recently shown that peroxyl radicals react with DNA to form alkali-labile sites. To further characterise these lesions, we studied their susceptibility to digestion by repair endonucleases that recognise different types of abasic sites. We found that peroxyl radical-damaged pSP189 plasmids were resistant to cleavage by T4 endonuclease V, an enzyme that incises DNA at "regular" and C4-oxidised abasic residues. In contrast, the DNA was digested by exonuclease III, an enzyme that recognises "regular" and C1-oxidised abasic sites. The presence of Trolox during exposure to peroxyl radicals reduced subsequent DNA cleavage by exonuclease III, while prior incubation of damaged plasmids with methoxyamine potentiated digestion by this enzyme. These findings suggest that peroxyl radical-induced DNA damage involves the generation of novel C1-oxidised deoxyribose residues.
Harkin
L A
LA
Department of Clinical and Experimental Pharmacology, The University of Adelaide, South Australia.
Burcham
P C
PC
D000578:Amidines; D001483:Base Sequence; D002839:Chromans / Q000494:pharmacology; D004249:DNA Damage; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D005090:Exodeoxyribonucleases / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D005609:Free Radicals; D008190:Lyases / Q000378:metabolism*; D008729:Methoxamine / Q000494:pharmacology; D010084:Oxidation-Reduction; D010545:Peroxides; D010957:Plasmids / Q000737:chemistry* / Q000187:drug effects
D000578:Amidines; D002839:Chromans; D016166:Free Radical Scavengers; D005609:Free Radicals; D010545:Peroxides; C049375:perhydroxyl radical; C046728:2,2'-azobis(2-amidinopropane); D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D043223:Deoxyribonuclease IV (Phage T4-Induced); D008190:Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008729:Methoxamine; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid