RsmG catalyzes N7-methylation of G527, the universally conserved loop of hairpin 18 in domain I of 16S rRNA in bacteria. In contrast to E. coli RsmG, which has been reported to recognize only intact 30S subunits, T. thermophilus RsmG shows no in vitro methylation activity against native 30S subunits, only low activity with 30S subunits at low magnesium concentration, and maximum activity with deproteinized 16S rRNA. Therefore T. thermophilus probably works on early assembly intermediate of ribosome biogenesis. Also, as other bacteria, the T. thermophilus rsmG mutants acquires resistance to aminoglycoside antibiotic streptomycin. AdoMet is the methyl group donor.