title: Tetracycline/H+ antiport and Na+/H+ antiport catalyzed by the Bacillus subtilis TetA(L) transporter expressed in Escherichia coli.
abstract: The properties of TetA(L)-dependent tetracycline/proton and Na+/proton antiport were studied in energized everted vesicles of Escherichia coli transformed with a cloned tetA(L) gene (pJTA1) from Bacillus subtilis. Inhibition patterns by valinomycin and nigericin indicated that both antiports were electrogenic, in contrast to the tetracycline/proton antiport encoded by gram-negative plasmid tet genes. Tetracycline uptake in the everted system was dependent upon a divalent cation, with cobalt being the preferred one. The apparent Km for tetracycline was markedly increased at pH 8.5 versus pH 7.5, whereas the Vmax was unchanged. The much higher apparent Km for Na+ decreased at pH 8.5 relative to that at pH 7.5, as did the Vmax. Na+ did not affect tetracycline uptake, nor did Co2+ and/or tetracycline affect Na+ uptake; complex patterns of inhibition by amiloride and analogs thereof were observed.
authors.affiliation: Department of Biochemistry, Mount Sinai School of Medicine of CUNY, New York 10029, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Guffanti
authors.forename: T A
authors.initials: TA
authors.lastname: Krulwich
mesh_terms: D017920:Antiporters / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects*; D003035:Cobalt / Q000493:pharmacokinetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D017136:Ion Transport; D009550:Nigericin / Q000494:pharmacology; D012965:Sodium Chloride / Q000493:pharmacokinetics; D017923:Sodium-Hydrogen Exchangers / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013752:Tetracycline / Q000493:pharmacokinetics; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D017920:Antiporters; D001426:Bacterial Proteins; D017923:Sodium-Hydrogen Exchangers; C079051:tetA protein, Bacteria; D014634:Valinomycin; D003035:Cobalt; D012965:Sodium Chloride; D013752:Tetracycline; D009550:Nigericin