Escherichia coli Kasugamycin Dependence Arising from Mutation at the rpsI Locus

Escherichia coli mutants with alterations in the electrophoretic mobility of ribosomal protein S9 were used to locate rpsI, the gene for this protein, on the linkage map. rpsI was located at about 70 min, roughly halfway between argG and fabE. It was very close to the gene for ribosomal protein L13, rplM. Another mutation at the rpsI locus gave rise to a phenotype of kasugamycin dependence and resistance. In this mutant, dependence on antibiotic came from kasugamycin being necessary to slow the rate of protein synthesis.