title: Excision repair of O6-methylguanine synthesized at the rat H-ras N-methyl-N-nitrosourea activation site and introduced into Escherichia coli.
abstract: O6-methylguanine (O6-methylG) is believed to be the premutagenic lesion responsible for mutational activation of the H-ras proto-oncogene in rats treated with N-methyl-N-nitrosourea (MNU). Research on the repair of O6-methylG has primarily focused on the methyltransferases. Potentially, other repair proteins may be involved in repair of O6-methylG. We have investigated the effect of Escherichia coli UvrABC excision repair on O6-methylG synthesized at the rat H-ras MNU activation site in a partial rat H-ras sequence constructed in an M13mp vector. An oligonucleotide self-selection technique was used to identify progeny phage containing DNA replicated from the O6-methylG-containing strand. We found that excision repair can help protect against mutation by O6-methylG at the rat H-ras MNU activation site.
authors.affiliation: Lineberger Cancer Research Center, University of North Carolina Medical School, Chapel Hill 27599-7295.
authors.forename: S C
authors.initials: SC
authors.lastname: Rossi
authors.forename: M
authors.initials: M
authors.lastname: Conrad
authors.forename: J M
authors.initials: JM
authors.lastname: Voigt
authors.forename: M D
authors.initials: MD
authors.lastname: Topal
mesh_terms: D001483:Base Sequence; D004260:DNA Repair; D004926:Escherichia coli / Q000235:genetics*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D008770:Methylnitrosourea / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011519:Proto-Oncogenes; D014162:Transfection
chemical_list: D006147:Guanine; D008770:Methylnitrosourea; C008449:O-(6)-methylguanine