Mutagenesis of theN-(Deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine DNA Adduct in Mammalian Cells SEQUENCE CONTEXT EFFECTS

摘要: Abstract Site-specifically modified oligodeoxynucleotides were used to investigate the mutagenic properties of a major cooked food mutagen-derived DNA adduct,N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (dG-C8-PhIP). dG-C8-PhIP-modified prepared by reacting an oligodeoxynucleotide containing single dG (5′-TCCTCCTX GCCTCTC, where X = C, A, G, or T) with N-acetoxy-PhIP. The unmodified and oligomers inserted into single-stranded phagemid vectors. These vectors transfected simian kidney (COS-7) cells. progeny plasmid obtained was transform Escherichia coli DH10B. When dC at 5′-flanking position dG-C8-PhIP, preferential incorporation dCMP, correct base, observed opposite dG-C8-PhIP. Targeted G → T transversions detected, along lesser amounts A transitions C transversions. No mutations detected for vector. influence sequence context on dG-C8-PhIP mutation frequency spectrum also explored. base replaced dT, dA, dG, mutational spectra similar that dC-flanking base. Higher frequencies (28–30%) when 5′ lower (13%) dA lesion. Single-base deletions only dT flanked adduct. We conclude is mutagenic, generating primarily in mammalian specificity vary depending neighboring context.