preferred_name: [TtuB sulfur-carrier protein]-Gly-NH-CH2-C(O)SH + 5-methyluridine(54) in tRNA + ATP + H2O <=> [TtuB sulfur-carrier protein]-C-terminal Gly-Gly + 5-methyl-2-thiouridine(54) in tRNA + AMP + diphosphate + 2 H(+)