23S rRNA (uracil<sup>1939</sup>-C<sup>5</sup>)-methyltransferase (, RumA, RNA uridine methyltransferase A, YgcA) is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (uracil<sup>1939</sup>-C<sup>5</sup>)-methyltransferase. This enzyme catalyses the following chemical reaction
The enzyme specifically methylates uracil<sup>1939</sup> at C<sup>5</sup> in 23S rRNA.