Figure 12

Exonuclease activity of wt-saPolX to remove 8oxodGMP present at primer terminus. Time-course analysis of exonuclease activity exhibited on gapped DNA bearing 8oxodG incorporated opposite templating C (C:8oxodG) and A (A:8oxodG) nucleotides in the presence of Mn²⁺ by wt-saPolX (12.5 nM) (A,B) and H435A mutant (12.5 nM) (C,D), respectively, are displayed. LC represents the loading control added in each lane for quantification. The decrease in the levels of the substrates bearing 8oxodGMP at the 3′ end in the presence of Mn²⁺ is shown in graph (E). The amount of substrate remaining after 120 min of incubation for DNA substrates C:8oxodG, A:8oxodG and C:G are compared (bar graph F). These experiments show that wt-saPolX can excise out mis-incorporated oxidized nucleotides in the presence of Mn²⁺ ions.