Energetics of tetracycline transport into Escherichia coli

The nature of energy coupling for the active transport of tetracycline into Escherichia coli was examined under conditions in which antibiotic uptake was directly compared with transport of proline (proton motive force dependent) and glutamine (phosphate bond dependent). Tetracycline transport was partially inhibited by osmotic shock and by exposure of bacteria to arsenate, two procedures which substantially reduced glutamine transport. Tetracycline transport was also partially inhibited in an uncB mutant (AN283) exposed to the uncoupler carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) under conditions that inhibited proline transport. Taken together, these data indicate involvement of both phosphate bond hydrolysis and the proton motive force for the active transport of tetracycline into E. coli.