FIG. 3.

Mg-dependent AP endonuclease activities in H. pylori X47 nucT and X47 nucT HP1526. Activities were determined on the indicated amounts of total cell extracts from H. pylori X47 nucT (lanes 3 to 6) or X47 nucT HP1526 (lanes 7 and 8) by use of a 34-mer oligonucleotide harboring the AP site analog (F) at position 16 of the labeled strand. Reactions were carried out in the presence (lanes 1 to 5 and 7 to 8) or absence (lane 6) of Mg ions. Reaction products were analyzed as described in the legend for Fig. 2. Lane 2 corresponds to the activity of the human APE1 protein as a control.