Sites of action of two ribosomal RNA methylases responsible for resistance to aminoglycosides

Abstract

Methylation of either of two residues (G-1405 or A-1408) within bacterial 16 S ribosomal RNA results in high level resistance to specific combinations of aminoglycoside antibiotics. The product of a gene that originated in Micromonospora purpurea (an actinomycete that produces gentamicin) gives resistance to kanamycin plus gentamicin by converting residue G-1405 to 7-methylguanosine. Resistance to kanamycin plus apramycin results from conversion of residue A-1408 to 1-methyladenosine catalysed by the product of a gene from Streptomyces tenjimariensis.