The AlkB family demethylases AlkB, FTO, and ALKBH5 recognize differentially
methylated RNA/DNA substrates, which results in their distinct biological roles.
Here we identify key active-site residues that contribute to their substrate
specificity. Swapping such active-site residues between the demethylases leads
to partially switched demethylation activities. Combined evidence from X-ray
structures and enzyme kinetics suggests a role of the active-site residues in
substrate recognition. Such a divergent active-site sequence may aid the design
of selective inhibitors that can discriminate these homologue RNA/DNA
demethylases.
