Evidence that covalent complex formation between BCNU-treated oligonucleotides and E. coli alkyltransferases requires the O6-alkylguanine function.
Affiliation
Department of Biochemical and Clinical Pharmacology, St Jude Children's Research Hospital, Memphis, TN 38101.Issue Date
1990-07-11
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Show full item recordAbstract
Chloroethylnitrosoureas (CENUs) are thought to induce cytotoxic DNA interstrand cross-links via an initial reaction at O6-position of guanine, yielding a rearranged intermediate, O6,N1-ethanoguanine. Repair of these adducts by mammalian and bacterial DNA alkyltransferases blocks the formation of cross-links. Human alkyltransferase can form a covalent complex with DNA containing BCNU-induced cross-link precursors, but the nature of the DNA-protein linkage remains unknown. Using E. coli alkyltransferases expressed by the ada and ogt genes, we now demonstrate that both enzymes can form such complexes with CENU-treated DNA. We attribute this reaction to the O6-alkylguanine repair function, because an N-terminal fragment of the ada protein, which has only alkylphosphotriester repair activity, failed to form a similar complex. This result is consistent with the idea that complex formation requires an alkyltransferase reaction with a guanine adduct, such as O6,N1-ethanoguanine. It tends to exclude the possibility that such reactions simply involve alkylation of the enzyme by reactive DNA adducts such as chloroethylphosphate or chloroethylguanine.Citation
Evidence that covalent complex formation between BCNU-treated oligonucleotides and E. coli alkyltransferases requires the O6-alkylguanine function. 1990, 18 (13):3961-6 Nucleic Acids Res.Journal
Nucleic Acids ResearchDOI
10.1093/nar/18.13.3961PubMed ID
2197601Type
ArticleLanguage
enISSN
0305-1048ae974a485f413a2113503eed53cd6c53
10.1093/nar/18.13.3961