Isolation of Vibrio alginolyticus mutants defective in the respiration-coupled Na+ pump

When the respiration-coupled Na+ pump functions, V. alginolyticus is able to grow in the presence of an extremely high concentration of proton conductor, carbonylcyanide m-chlorophenylhydrazone. The mutants which became sensitive to the proton conductor were isolated and examined in regard to the Na+ pump activity. Although the activity of a respiration-dependent H+ extrusion by the mutants is comparable to that by the wild type, the Na+ pump activity of the mutants is significantly reduced. Furthermore, NADH oxidase of membranes isolated from the mutants is altered to be independent of Na+. It is concluded that the mutants have an alteration in the respiratory chain which simultaneously results in a lack of the Na+ pump.