Reversion of a streptomycin-dependent strain of Escherichia coli

Summary A streptomycin dependent, spectinomycin resistant mutant ofEscherichia coli was used to select spontaneous phenotypic revertants to non-dependence on streptomycin. The ribosomes from one such revertant, which is inhibited by both streptomycin and spectinomycin, were analyzedin vitro. The altered protein responsible for the suppression of the streptomycin dependent phenotype was identified; this protein is 30S-10. The genetic locus for this mutation is a newly identified locus and it has been positioned close to thestr locus. The identification of the altered component responsible for the suppression of the spectinomycin resistant phenotype may be the same as that for the streptomycin dependent phenotype, but this is unproven.