LOCALIZATION OF SENSITIVITY TO KANAMYCIN AND STREPTOMYCIN IN 30-S RIBOSOMAL PROTEINS OF ESCHERICHIA-COLI

The localization in ribosomes of sensitivity to kanamycin was investigated and compared with that to streptomycin, using ribosomes from a mutant of Escherichia coli resistant to both these antibiotics. It was demonstrated that the sensitivity to both antibiotics was located in the 30 S subunit. The 30 S subunit was fractionated into a 23 S core and split proteins 30, and the 23 S core was split further into core proteins 30 and 16 S ribosomal RNA. It was found that the sensitivity to kanamycin as well as to streptomycin resided in proteins of the 23 S core. To identify the responsible component, 30 S ribosomal proteins from the parent strain and from a kanamycin-resistant mutant were labelled differently, and co-chromatographed through carboxymethylcellulose column. Only one component (P 10) was observed to appear inconsistently in the elution profile, and it was therefore assumed to be the component that determined the sensitivity to kanamycin. This assumption was confirmed by examining the inhibition by kanamycin in poly U-directed incorporation of phenylalanine with 30 S subunits reconstituted in different combinations between P 10 and the other components from the two origins. This component and the component controlling sensitivity to streptomycin were identical. It was observed that the reconstituted ribosomes containing P 10 from either resistant mutant were resistant to both antibiotics, and P 10 protein in both mutants was altered. © 1969, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.