<p>The <taxon tax_id="562">Escherichia coli</taxon> Ada protein repairs O6-methylguanine residues and methyl phosphotriesters in DNA by direct transfer of the methyl group to a cysteine residue. This domain contains four conserved cysteines that form a zinc binding site [<cite idref="PUB00007287"/>, <cite idref="PUB00007288"/>]. One of these cysteines is a methyl group acceptor. The methylated domain can then specifically bind to the ada box on a DNA duplex [<cite idref="PUB00007288"/>].</p> Ada DNA repair, metal-binding