2.1.1.170 S-adenosyl-L-methionine + guanine527 in 16S rRNA - 2.1.1.170 S-adenosyl-L-methionine + guanine527 in 16S rRNA methylations concentrated in the decoding site of the 30S ribosomal subunit may act to fine tune codon recognition in a manner similar to tRNA modifications. The intact 30S subunit is very unlikely to be the natural substrate for Thermus thermophilus RsmG in vivo. This interpretation is consistent with the position of G527 in the intact 30S subunit, where it is buried and would be inaccessible for methylation without substantial unfolding of the local subunit structure. Deproteinized 16S rRNA is the most active substrate in vitro. In vivo, several ribosomal proteins probably begin binding to the nascent 16S rRNA transcript prior to its completion, making an early assembly intermediate a plausible candidate for the biological substrate of RsmG 2.1.1.170 S-adenosyl-L-methionine + guanine527 in 16S rRNA the methyltransferase RsmG methylates the N7 position of nucleotide G535 in 16S rRNA of Bacillus subtilis (corresponding to G527 in Escherichia coli). Nucleotide G527 is situated within a hairpin loop (the socalled 530 loop) that is one of the most highly conserved features of 16S rRNA