title: Hepsulfam induced DNA adducts and its excision repair by bacterial and mammalian 3-methyladenine DNA glycosylases.
abstract: A variety of alkylated base adducts are repaired by 3-methyladenine DNA glycosylases, one of the base excision repair enzymes. In this study, we examined the DNA adducts induced by hepsulfam and determined whether alkylated base adducts can be substrates for bacterial and mammalian 3-methyladenine DNA glycosylases by electrophoresis methods. Hepsulfam, a synthetic analogue of busulfan, is known to alkylate DNA and form interstrand cross-links. The extent of DNA interstrand cross-links induced by hepsulfam and busulfan was found to be similar but significantly lower than that induced by chlorambucil, as measured by an agarose gel assay. The major monofunctional alkylation site of hepsulfam was observed at the N7 position of guanine, and not at the N3 position of adenine. Both compounds did not exhibit any sequence selective DNA alkylation patterns. The excision of hepsulfam-induced DNA adducts has been determined by treatment with homogeneous recombinant bacterial, rat and human 3-methyladenine DNA glycosylases and successive treatments by formamidopyrimidine-DNA glycosylase. The Escherichia coli alkA protein was shown to completely excise N7 guanine adducts, whereas mammalian 3-methyladenine DNA glycosylase failed to excise them. In addition, the cytotoxicity assay showed that E. coli mutant strains defective in the alkA gene or the uvrA gene were more sensitive to killing by hepsulfam than the wild type.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Yeungnam University, Kyongsan, Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Je
authors.forename: J K
authors.initials: JK
authors.lastname: Son
authors.forename: T R
authors.initials: TR
authors.lastname: O'Connor
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
mesh_terms: D000478:Alkylation; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D001665:Binding Sites; D002066:Busulfan / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D018736:DNA Adducts / Q000187:drug effects*; D045647:DNA Glycosylases; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D006801:Humans; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000737:chemistry / Q000187:drug effects; D051381:Rats; D013451:Sulfonic Acids / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D018906:Antineoplastic Agents, Alkylating; D003432:Cross-Linking Reagents; D018736:DNA Adducts; D004269:DNA, Bacterial; D013451:Sulfonic Acids; D004247:DNA; C052475:hepsulfam; C021565:3-methyladenine-DNA glycosylase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C076131:DNA-3-methyladenine glycosidase II; D002066:Busulfan