Experimental verification of a sequence-based prediction:: F1F0-Type ATPase of Vibrio cholerae transports protons, not Na+ ions

The membrane energetics of the intestinal pathogen Vibrio cholerae involves both H+ and Na+ as coupling ions. The sequence of the c subunit of V cholerae F0F1 ATPase suggested that this enzyme is H+ specific, in contrast to the results of previous studies on the Na+-dependent ATP synthesis in closely related Vibrio spp. Measurements of the pH gradient and membrane potential in membrane vesicles isolated from wild-type and DeltaatpE mutant V cholerae show that the F1F0 ATPase of V. cholerae is an H+, not Na+, pump, confirming the bioinformatics assignments that were based on the Na+-binding model of S. Rahlfs and V. Muller (FEBS Lett. 404:269-271, 1999). Application of this model to the AtpE sequences from other bacteria and archaea indicates that Na+-specific F1F0 ATPases are present in a number of important bacterial pathogens.