ATP‐driven Na+ transport and Na+‐dependent ATP synthesis in Escherichia coli grown at low \ΔgmH+

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Abstract
In inverted subcellular vesicles of Escherichia coli grown at high \ΔgmH+ (neutral pH, no protonophorous uncoupler), ATP‐driven Na+ transport and oxidative phosphorylation are completely inhibited by the protonophore CCCP. If E coli was grown at low \ΔgmH+, i.e. at high pH or in the presence of uncoupler, some oxidative phosphorylation was observed in the vesicles even in CCCP‐containing medium, and Na+ transport was actually stimulated by CCCP. The CCCP‐resistant transport and phosphorylation were absent from the unc mutant lacking F0F1, ATPase. Both processes proved to be sensitive to (i) the Na+/H+ antiporter monensin, (ii) the Na+ uniporter ETH 157, (iii) the F0 inhibitors DCCD and venturicidin, and (iv) the F1 inhibitor aurovertin. The CCCP‐resistant oxidative phosphorylation was stimulated by Na+ and arrested by oppositely directed ΔpNa. These data are consistent with the assumption that, under appropriate growth conditions, the F0F1‐type ATPase of E. coli becomes competent in transporting Na+ ions.