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 In the N-terminal section; belongs to the methyltransferase superfamily. RNA methyltransferase RsmG family. In the C-terminal section; belongs to the class IV-like SAM-binding methyltransferase superfamily. RNA methyltransferase TrmH family.