label: 5-methyluridine(1939) in 23S rRNA + S-adenosyl-L-homocysteine + H(+) => uridine(1939) in 23S rRNA + S-adenosyl-L-methionine
label_lc: 5-methyluridine(1939) in 23s rrna + s-adenosyl-l-homocysteine + h(+) => uridine(1939) in 23s rrna + s-adenosyl-l-methionine