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Stoichiometry of metal-tetracycline/H+ antiport mediated by transposon Tn10-encoded tetracycline resistance protein in Escherichia coli
Abstract
The tetracycline resistance protein (TetA) endoded by transposon Tn10 mediates the efflux of divalent cation-tetracycline chelating complexes [Yamaguchi, A., Udagawa, T. and Sawai, T. (1990) J. Biol. Chem. 265, 4809–4813]. It was confirmed that protons were antiported with the complexes through an electrically-neutral process because the antiport consumed ΔpH but not Δψ. The quantitative relationship between ΔpH and ΔpTC determined by a flow-dialysis method clearly indicated a 1:1 stoichiometry of the monocationic metal-tetracycline/H+ exchange.
