uridine(54) in tRNA + S-adenosyl-L-methionine => 5-methyluridine(54) in tRNA + S-adenosyl-L-homocysteine + H(+)
uridine(54) in trna + s-adenosyl-l-methionine => 5-methyluridine(54) in trna + s-adenosyl-l-homocysteine + h(+)