Specifically methylates the N7 position of guanine in position 527 of 16S rRNA. guanosine(527) in 16S rRNA + S-adenosyl-L-methionine = N(7)-methylguanosine(527) in 16S rRNA + S-adenosyl-L-homocysteine A mutant in which deletion of the last 50 residues in ubiA is combined with the Tyr-56 mutation in rsmG is highly resistant to streptomycin and has a small colony phenotype (which grow slowly and are resistant to aminoglycoside anitbiotics). Belongs to the methyltransferase superfamily. RNA methyltransferase RsmG family.