Figure 4.

DNA pol β catalyzed DNA synthesis modulated by gapped DNA and a minor-groove BPDE-adduct. (A) Schematic of DNA substrates for DNA synthesis reactions. The bold G indicates the position of the unadducted C₁₀S BPDE-dG or C₁₀R BPDE-dG. The radio-labeled primer strand is indicated by the 5′-³²P label. (B) DNA synthesis reactions (15 min) using an unadducted template without (−) or with (+) a downstream unlabeled oligonucleotide strand. Lanes 1–2, 3–4, 5–6, 7–8, and 9–10 include pol β (10 fmol) with 0.5, 5, 10, 50, and 100 nM dCTP, respectively. (C) DNA synthesis reactions (15 min) using the C₁₀S BPDE-dG adducted template without (−) or with (+) a downstream unlabeled oligonucleotide strand. Lanes 1–2, 3–4, 5–6, 7–8, and 9–10 include pol β (10 fmol) with 25, 50, 100, 200, and 500 μM, respectively. (D) DNA synthesis reactions (15 min) using the C₁₀R BPDE-dG adducted template without (−) or with (+) a downstream unlabeled oligonucleotide strand. Lanes 1–2, 3–4, 5–6, 7–8, and 9–10 include pol β (10 fmol) with 100, 200, 500, 1000, and 1500 μM dCTP, respectively.