InterPro domain: IPR040072

The enzymes in this subgroup represent the Class A Radical SAM Methyltransferases. These proteins all have a single canonical Radical SAM core domain and utilise a methylene radical generated on a unique methylated cysteine residues. They use two moles of SAM per turnover, the first being a methyl donor, methylating the conserved Cys residue and the other being reductively cleaved to form the 5'-deoxyadenosyl radical and Methionine [ 1 , 2 , 3 , 4 , 5 , 6 ].

1. Radical-mediated enzymatic methylation: a tale of two SAMS. Acc. Chem. Res. 45, 555-64
2. Radical SAM-mediated methylation reactions. Curr Opin Chem Biol 17, 597-604
3. Mechanistic diversity of radical S-adenosylmethionine (SAM)-dependent methylation. J. Biol. Chem. 290, 3995-4002
4. Radical SAM-Mediated Methylation of Ribosomal RNA. Meth. Enzymol. 560, 355-76
5. Cfr and RlmN contain a single [4Fe-4S] cluster, which directs two distinct reactivities for S-adenosylmethionine: methyl transfer by SN2 displacement and radical generation. J. Am. Chem. Soc. 133, 19586-9
6. Antibiotic resistance evolved via inactivation of a ribosomal RNA methylating enzyme. Nucleic Acids Res. 44, 8897-8907