Fig 3. The oxidized abasic lesion DOB inhibits pol β DNA synthesis activity during BER in a small CAG hairpin loop.

The effect of the type of abasic lesion on pol β synthesis activity with a short (CAG)₃/(CAG)₂ double-flap intermediate formed during BER of a (CAG)₅ hairpin was examined by measuring pol β synthesis activity on the substrate containing a DOB (left panel), native sugar (middle panel), or THF (right panel). Lanes 1, 7, and 13 indicate the substrate only. Lanes 2–6, lanes 8–12, and lanes 14–18 indicate the substrate incubated with pol β (2.5 nM) for a time course of 2, 5, 10, 15, and 30 minutes. Substrates were ³²P-labeled at the 5’-end of the upstream strand and are illustrated above each gel. The experiments were repeated at least three times. Representative gels are shown. The quantification of the data is presented below the gels. Two-way ANOVA with Tukey’s multiple comparison posttests was used to determine statistically significant differences. "*" denotes P < 0.05, compared to the DOB-containing substrates.