Figure 7.

Extension by DNA polymerase after removal of 3′-terminal AP site analogues. (a) ssDNA and (b–d) 3′-recessive dsDNA with a 3′-terminal Spacer (Spacer C3, C6, or C12) or a normal nucleotide were incubated with 10 nM TeuendoIV alone (a,b) at 55 °C for the indicated time. The 3′-recessive dsDNA were incubated with Sulfolobus acidocaldarius DNA polymerase IV at 50 °C for the indicated time in the (c) absence or (d) presence of 10 nM TeuendoIV. After removing terminal AP sites with TeuendoIV at 50 °C for 5 min (d), the DNA polymerase was added into reaction mixtures, and then an additional incubation was performed. The cleavage and extension percentages of substrates are listed at the bottom of each panel. The symbol of black asterisk and the red letter X denote the fluorescein (6-FAM) group at the 5′-end and the AP-sites, respectively.