Figure 6.

PHP-dependent activities of mutants at PolXBs residue Lys192. (A) 3′-5′ exonuclease activity. The assay was performed as described in ‘Materials and Methods’ section, incubating 1.5 nM of a 2-nt gapped structure with 32 nM of either the wild-type or the indicated mutant PolXBs in the presence of 1 mM of MnCl₂ for the indicated period at 30°C. (B) AP-endonuclease activity. The assay was carried out as described in ‘Materials and Methods’ section, incubating 1.5 nM of a 34mer double stranded oligonucleotide containing an internal THF group with 64 nM of either the wild-type or the indicated mutant PolXBs in the presence of 1 mM of MnCl₂ for the indicated period at 30°C.