DNA-binding protein involved in single-strand DNA break repair, double-strand DNA break repair and base excision repair. Resolves abortive DNA ligation intermediates formed either at base excision sites, or when DNA ligases attempt to repair non-ligatable breaks induced by reactive oxygen species. Catalyzes the release of adenylate groups covalently linked to 5'-phosphate termini, resulting in the production of 5'-phosphate termini that can be efficiently rejoined. Also able to hydrolyze adenosine 5'-monophosphoramidate (AMP-NH(2)) and diadenosine tetraphosphate (AppppA), but with lower catalytic activity (By similarity). Likewise, catalyzes the release of 3'-linked guanosine (DNAppG) and inosine (DNAppI) from DNA, but has higher specific activity with 5'-linked adenosine (AppDNA) (By similarity). a 5'-end adenosine-5'-diphospho-5'-(2'-deoxyribonucleoside)-DNA + H2O = a 5'-end 5'-monophospho-2'-deoxyribonucleoside-DNA + AMP + 2 H(+) a 5'-end adenosine-5'-diphospho-5'-ribonucleoside-2'-deoxyribonucleotide-DNA + H2O = a 5'-end 5'-monophospho-ribonucleoside-2'-deoxyribonucleotide-DNA + AMP + 2 H(+) a 3'-end 2'-deoxyribonucleotide-3'-diphospho-5'-guanosine-DNA + H2O = a 3'-end 2'-deoxyribonucleotide 3'-phosphate-DNA + GMP + 2 H(+) The histidine triad, also called HIT motif, forms part of the binding loop for the alpha-phosphate of purine mononucleotide. The HIT domain is required for enzymatic activity. The C2H2-type zinc finger mediates DNA-binding.