RsmF methylates C1407 in the stem of helix 44 near the 3’-end of 16S rRNA within assembled 30S subunits (it does not work on naked 16S rRNA or within tight-couple 70S ribosome). The ribosomal protein S12 is specially important. The enzyme has an N-terminal SAM-binding catalytic domain with structural similarity to the equivalent domains in several other m5C RNA MTases (including RsmB). However, E. coli RsmF has also a C-terminal PUA-domain similar to that in pseudouridine synthases (Pus) and archaeosine-specific transglycosylases (Tgt). It also contains extended regions of positive electrostatic potential that differ from other RNA MTase structures. Methylation of C1407 by RsmF is impeded by Sgm methyltransferase that catalyzes the formation of m7G on its adjacent G1405 target on the 30S ribosomal subunit. Thus resistance to certain aminoglycosides depends on the interplay of two different methyltransferases: RsmF and Sgm. RsmF is conserved in bacteria.