A Methyltransferase Catalyzing Reactions More Than Methylation

-methylations. Gene inactivation, biochemical characterization, substrate/product cocrystallization, and site-specific mutagenesis rationalized the mechanisms by which the MT-fold of MitM is repurposed to deliver such an extraordinary capability, facilitating the observation of a few new antitumor mitomycins that were not recognized previously in the producing strain. This study attracts attention to uncharacterized MT-fold proteins, which have millions of sequences in databases but remain to be appreciated in catalytic function.