title: Excision repair of 2,5-diaziridinyl-1,4-benzoquinone (DZQ)-DNA adduct by bacterial and mammalian 3-methyladenine-DNA glycosylases.
abstract: The mechanisms of anticancer activity of 2,5-diaziridinyl-1,4-benzoquinone (DZQ) are believed to involve the alkylation of guanine and adenine bases. In this study, it has been investigated whether bacterial and mammalian 3-methyladenine-DNA glycosylases are able to excise DZQ-DNA adduct with a differential substrate specificity. DZQ-induced DNA adduct was first formed in the radiolabeled restriction enzyme DNA fragment, and excision of the DNA adduct was analyzed following treatment with homogeneous 3-methyladenine-DNA glycosylase from E. coli, rat, and human, respectively. Abasic sites generated by DNA glycosylases were cleaved by the associated lyase activity of the E. coli formamidopyrimidine-DNA glycosylase. Resolution of cleaved DNA on a sequencing gel with Maxam-Gilbert sequencing reactions showed that DZQ-induced adenine and guanine adducts were very good substrates for bacterial and mammalian enzymes. The E. coli enzyme excises DZQ-induced adenine and guanine adducts with similar efficiency. The rat and human enzymes, however, excise the adenine adduct more efficiently than the guanine adduct. These results suggest that the 3-methyladenine-DNA glycosylases from different origins have differential substrate specificity to release DZQ-DNA lesions. The use of 3-methyladenine-DNA glycosylase incision analysis could possibly be applied to quantify a variety of DNA adducts at the nucleotide level.
authors.affiliation: Department of Biochemistry and Institute of Natural Sciences, Yeungnam University, Kyongsan, Korea. cslee@yu.ac.kr
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism; D001388:Aziridines / Q000378:metabolism*; D016227:Benzoquinones / Q000378:metabolism*; D018736:DNA Adducts / Q000378:metabolism*; D045647:DNA Glycosylases; D004260:DNA Repair; D043382:DNA-Formamidopyrimidine Glycosylase; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006801:Humans; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D051381:Rats; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity
chemical_list: D000970:Antineoplastic Agents; D001388:Aziridines; D016227:Benzoquinones; D018736:DNA Adducts; D029968:Escherichia coli Proteins; C009970:ethylenimine quinone; C021565:3-methyladenine-DNA glycosylase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli