The Mrp Na + /H + Antiporter Increases the Activity of the Malate:Quinone Oxidoreductase of an Escherichia coli Respiratory Mutant

Abstract
Mrp catalyzes secondary Na + /H + antiport and was hypothesized to have an additional primary energization mode. Mrp-dependent complementation of nonfermentative growth of an Escherichia coli respiratory mutant supported this hypothesis but is shown here to be related to increased expression of host malate:quinone oxidoreductase, not to catalytic activity of Mrp.