23S rRNA (guanine<sup>745</sup>-N<sup>1</sup>)-methyltransferase (, Rlma(I), Rlma1, 23S rRNA m1G745 methyltransferase, YebH, RlmAI methyltransferase, ribosomal RNA(m1G)-methylase, rRNA(m1G)methylase, RrmA, 23S rRNA:m1G745 methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (guanine<sup>745</sup>-N<sup>1</sup>)-methyltransferase. This enzyme catalyses the following chemical reaction
The enzyme specifically methylates guanine<sup>745</sup> at N<sup>1</sup> in 23S rRNA.