DELTA-PSI AND DELTA-PH GENERATION BY THE H+ PUMPS OF THE RESPIRATORY-CHAIN AND ATPASE IN SUBCELLULAR VESICLES FROM MARINE BACTERIUM VIBRIO-ALGINOLYTICUS

Succinate and glycerol 3-phosphate oxidation and coupled Δψ generation by the respiratory chain of inside-out subcellular vesicles of Vibrio alginolyticus do not depend on Na+ concentration and are not suppressed by submicromolar concentrations of 2-heptyl-4-hydroxyquinoline N-oxide, arresting Na+-motive NADH:quinone reductase. When the H+-permeability of membranes is diminished by adding Mg2+ and by N,N′-dicyclohexylcarbodiimide treatment, Na+-independent NADH oxidation appears to be competent in the Δψ generation. NADH and succinate oxidations and ATP-hydrolysis result in ΔpH formation (inside acidic) in media with K+ and valinomycin. Na+-dependent NADH oxidation also participates in Δ \ ̄gmH+ generation because the inhibition of Na+-motive NADH:quinone reductase (a medium with 2-heptyl-4-hydroxyquinoline N-oxide and without added Na+) slows down ΔpH formation. It is assumed that the NADH-quinone and quinole-O2 steps of the respiratory chain are Na+- and H+-motive, respectively. Since ATP hydrolysis by the V. alginolyticus vesicles supports uphill transport of Na+ (Dibrov, P.A., Skulachev, V.P., Sokolov, M.V. and Verkhovskaya, M.L. (1988) FEBS Lett. 233, 355-358) as well as of H+ (this paper), we may conclude that Na+-cycle and H+-cycle co-exist in the membrane of this bacterium. © 1990.