May nick NaeI sequences that contain T/G mispairs resulting from m5C-deamination. If unrepaired, these mismatches can lead to C-to-T transition mutations. The very short patch (VSP) repair process counteracts the mutagenic process by repairing the mismatches in favor of the G-containing strand. This enzyme is an endonuclease that nicks double-stranded DNA within the sequence GCCGGC (C-methylation site unknown) next to the thymidine residue that is mismatched to 2'-deoxyguanosine. The incision is mismatch-dependent and strand-specific. Belongs to the Vsr family.