This is a C-terminal TRAM (after TRM2, a family of uridine methylases, and MiaB) domain found in the methylthiotransferases RimO enzymes that catalyze the conversion of aspartate to 2-methylthio-aspartate (msD) in the S12 protein near the decoding center in prokaryotic ribosomes. The TRAM domain in RimO, contains five anti-parallel beta-strands and docks on the surface of the Radical-SAM domain at the distal edge of its open TIM-barrel from its conserved [4Fe-4S] cluster [1].

1: Two Fe-S clusters catalyze sulfur insertion by radical-SAM methylthiotransferases. Forouhar F, Arragain S, Atta M, Gambarelli S, Mouesca JM, Hussain M, Xiao R, Kieffer-Jaquinod S, Seetharaman J, Acton TB, Montelione GT, Mulliez E, Hunt JF, Fontecave M; Nat Chem Biol. 2013;9:333-338. PMID:23542644