Alteration of ribosomal protein S17 by mutation linked to neamine resistance in Escherichia coli: I. General properties of neaA mutants

Abstract

A mutant of Escherichia coli strain K12S isolated after selection for resistance to the amino glycoside antibiotic neamine shows severe restriction of amber suppressors in vivo . Ribosomes from the mutant exhibit low neamine-induced misreading in vitro and a decreased affinity for the related antibiotic streptomycin. The S17 ribosomal protein from the mutant strain shows altered electrophoretic mobility on two-dimensional polyacrylamide gels and also differs in chromatographical behaviour from the S17 protein from the parental strain. When ribosomes from the mutant strain are reconstituted in the presence of a molar excess of the S17 protein from the wild type species, the particles exhibit normal druginduced misreading properties as well as a normal capacity for binding streptomycin. The gene involved in the alteration of protein S17 ( rpxQ ) is located inside the ribosomal protein gene cluster at 64 minutes on the E. coli genetic map and cotransduces at 96% with rpxE (S5).