Involved in base excision repair of DNA damaged by oxidation or by mutagenic agents. Acts as DNA glycosylase that recognizes and removes damaged bases. Has a preference for oxidized purines, such as 7,8-dihydro-8-oxoguanine (8-oxoG) when paired with C, G or T, as well as methyl-faPy (formanidopyrimidine residues) in poly(dG-dC) and spiroiminodihydantoin:C base pairs. Unlike its E.coli ortholog has no activity on 8-oxoG:A. Has AP (apurinic/apyrimidinic) lyase activity and introduces nicks in the DNA strand. Cleaves the DNA backbone by beta-delta elimination to generate a single-strand break at the site of the removed base with both 3'- and 5'-phosphates. Cleaves ssDNA containing an AP site. Complements the H(2)O(2) sensitivity of an M.smegmatis fpg disruption mutant; upon expression in M.smegmatis excises 8-oxoG from dsDNA. Hydrolysis of DNA containing ring-opened 7-methylguanine residues, releasing 2,6-diamino-4-hydroxy-5-(N-methyl)formamidopyrimidine. 2'-deoxyribonucleotide-(2'-deoxyribose 5'-phosphate)-2'-deoxyribonucleotide-DNA = a 3'-end 2'-deoxyribonucleotide-(2,3-dehydro-2,3-deoxyribose 5'-phosphate)-DNA + a 5'-end 5'-monophospho-2'-deoxyribonucleoside-DNA + H(+) Binds 1 zinc ion per subunit. Monomer. Expressed in mid-log phase. Belongs to the FPG family.