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