Mutagenicity Analysis of C8-Phenoxy-Guanine in the NarI Recognition DNA Sequence

Phenoxyl radicals can covalently attach to the C8-site of 2′-deoxyguanosine (dG) to generate oxygen-linked biaryl ether C8-dG adducts. To determine the mutagenicity of an O-linked C8- dG adduct, C8-phenoxy-dG (PhOdG) was incorporated into the G3 position (X) of the NarI recognition sequence within a 22-mer oligonucleotide template (5′-CTCGGCX-CCATCCCTTACGAGC, where X = dG, or PhOdG) using solid-phase DNA synthesis. The NarI(22) template was annealed to a 15-mer primer and in vitro mutagenicity was assessed using primer-extension assays with a high-fidelity replicative polymerase, Escherichia coli pol I Klenow fragment exo− (Kf−), and a lesion-bypass Y-family polymerase, Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4). These studies predict that the O-linked C8-dG lesion PhOdG will have a low mutagenic effect, and is unlikely to contribute strongly to phenol toxicity.