title: Respiratory Na+ pump and Na+-dependent energetics in Vibrio alginolyticus.
abstract: The marine bacterium Vibrio alginolyticus was found to possess the respiratory Na+ pump that generates an electrochemical potential of Na+, which plays a central role in bioenergetics of V. alginolyticus, as a direct result of respiration. Mutants defective in the Na+ pump revealed that one of the two kinds of NADH: quinone oxidoreductase requires Na+ for activity and functions as the Na+ pump. The Na+ pump composed of three subunits was purified and reconstituted into liposomes. Generation of membrane potential by the reconstituted proteoliposomes required Na+. The respiratory Na+ pump coupled to the NADH: quinone oxidoreductase was found in wide varieties of Gram-negative marine bacteria belonging to the genera Alcaligenes, Alteromonas, and Vibrio, and showed a striking similarity in the mode of electron transfer and enzymic properties. Na+ extrusion seemed to be coupled to a dismutation reaction, which leads to the formation of quinol and quinone from semiquinone radical.
authors.affiliation: Institute of Applied Microbiology, University of Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tokuda
mesh_terms: D004734:Energy Metabolism; D012964:Sodium / Q000378:metabolism*; D014733:Vibrio / Q000378:metabolism*
chemical_list: D012964:Sodium