16S rRNA (guanine<sup>1405</sup>-N<sup>7</sup>)-methyltransferase (, methyltransferase Sgm, m7G1405 Mtase, Sgm Mtase, Sgm, sisomicin-gentamicin methyltransferase, sisomicin-gentamicin methylase, GrmA, RmtB, RmtC, ArmA) is an enzyme with systematic name S-adenosyl-L-methionine:16S rRNA (guanine<sup>1405</sup>-N<sup>7</sup>)-methyltransferase. This enzyme catalyses the following chemical reaction
The enzyme specifically methylates guanine<sup>1405</sup> at N<sup>7</sup> in 16S rRNA.