Residue aspartate-147 from the third transmembrane region of Na(+)/H(+) antiporter NhaB of Vibrio alginolyticus plays a role in its activity

Abstract

NhaB is a bacterial Na(+)/H(+) antiporter with unique topology. The pH dependence of NhaB from Vibrio alginolyticus differs from that of the Escherichia coli NhaB homolog. Replacement of Asp-147 with Glu made high H(+) concentrations a requirement for the NhaB activity. Replacement of Asp-147 with neutral amino acids inactivated NhaB.