Figure 2.

DNA pol β catalyzed DNA synthesis modulated by gapped DNA and a major-groove BPDE-adduct. (A) Schematic of DNA substrates for DNA synthesis reactions. The bold A indicates the position of the unadducted, C₁₀S BPDE-dA or C₁₀R BPDE-dA. The radio-labeled primer strand is indicated by the 5′-³²P label. (B) DNA synthesis reactions using an unadducted template without (−) or with (+) a downstream unlabeled oligonucleotide strand. Odd and even numbered lanes represent 5 and 15 min reactions, respectively. Lanes 1–4, 5–8, 9–12, and 13–16 include pol β (10 fmol) with 0.1, 0.2, 0.5, and 1 μM dTTP, respectively. (C) DNA synthesis reactions using the C₁₀S BPDE-dA adducted template without (−) or with (+) a downstream unlabeled oligonucleotide strand. Odd and even numbered lanes represent 5 and 15 min reactions, respectively. Lanes 1–4, 5–8, 9–12, 13–16, and 17–20 include pol β (10 fmol) with 100, 200, 500, 1000, and 1500 μM dTTP, respectively. (D) DNA synthesis reactions using the C₁₀R BPDE-dA adducted template without (−) or with (+) a downstream unlabeled oligonucleotide strand. Odd and even numbered lanes represent 5 and 15 min reactions, respectively. Lanes 1–4, 5–8, 9–12, 13–16, and 17–20 include pol β (10 fmol) with 2.25, 2.5, 2.75, 3, and 3.25 mM dTTP, respectively.