Members of this family are S-adenosylmethionine-dependent methyltransferases from gamma-proteobacterial species. The diversity in the roles of methylation is matched by the almost bewildering number of methyltransferase enzymes that catalyze the methylation reaction. Although several classes of methyltransferase enzymes are known, the great majority of methylation reactions are catalyzed by the S-adenosylmethionine-dependent methyltransferases.