Is involved in the adaptive response to alkylation damage in DNA caused by alkylating agents. Repairs the Sp diastereomer of DNA methylphosphotriester lesions by a direct and irreversible transfer of the methyl group to one of its own cysteine residues. Also catalyzes the hydrolysis of the deoxyribose N-glycosidic bond to excise 3-methyladenine, 3-methylguanine, 7-methylguanine, O2-methylthymine, and O2-methylcytosine from the damaged DNA polymer formed by alkylation lesions (By similarity). The methylation of Alka by methylphosphotriesters in DNA leads to its activation as a transcriptional regulator that activates the transcription of its own gene and other alkylation resistance genes. (2'-deoxyribonucleoside 5'-methylphosphotriester)-DNA + L-cysteinyl-[protein] = 2'-deoxyribonucleotide-DNA + H(+) + S-methyl-L-cysteinyl-[protein] Hydrolysis of alkylated DNA, releasing 3-methyladenine, 3-methylguanine, 7-methylguanine and 7-methyladenine. Binds 1 zinc ion per subunit. Co-immunoprecipitates with DarG in the presence and absence of darT. This enzyme catalyzes only one turnover and therefore is not strictly catalytic. According to one definition, an enzyme is a biocatalyst that acts repeatedly and over many reaction cycles. In the C-terminal section; belongs to the alkylbase DNA glycosidase AlkA family.