OppA Escherichia coli mutants have osmodependent resistance to aminoglycoside antibiotics

the oligopeptide permease (oppa) protein was found to be missing in the periplasmic fractions of escherichia coli kanamycin-resistant mutants selected under high osmotic conditions. the growth behavior of one mutant in media containing kanamycin or the toxic peptide triornithine suggests that oppa and another cell envelope component contribute to the osmolarity-dependent aminoglycoside resistance of e. coli.