Energetics of tetracycline efflux system encoded by Tn10 in Escherichia coli.
Tritiated tetracycline was actively accumulated in inverted membrane vesicles prepared from Escherichia coli W3104rif, which has a transposon, Tn10, on the plasmid, R388, by means of a protonmotive force when NADH was added as an energy source. The tetracycline accumulation was reduced to about one-half the full value on the addition of a cation/proton-exchange ionophore, nigericin. In contrast, remarkable stimulation of the tetracycline accumulation was observed with a K+-specific ionophore, valinomycin. The accumulation of [3H]tetracycline could also be driven by an artificially imposed interior-acidic pH gradient (delta pH), but not, however, by an artificially imposed interior-positive membrane potential (delta psi). These results strongly indicate that the plasmid-encoded tetracycline transport was mainly due to an electrically neutral proton/tetracycline antiport system.
D001692:Biological Transport / Q000187:drug effects; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004734:Energy Metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials; D009243:NAD / Q000502:physiology; D013752:Tetracycline / Q000378:metabolism* / Q000494:pharmacology
D007476:Ionophores; D009243:NAD; D013752:Tetracycline