Transmembrane segment II of NhaA Na+/H+ antiporter lines the cation passage, and Asp65 is critical for pH activation of the antiporter.

ABSTRACT: The crystal structure of Escherichia coli NhaA determined at pH 4 has provided insights into the mechanism of activity of a pH-regulated Na+/H+ antiporter. However, because NhaA is activated at physiological pH (pH 5.5-8.5), many questions related to the active state of NhaA have remained elusive. Our experimental results at physiological pH and computational analyses reveal that amino acid residues in transmembrane segment II contribute to the cation pathway of NhaA and its pH regulation: 1) transmembrane segment II is a highly conserved helix and the conserved amino acid residues are located on one side of the helix facing either the cytoplasmic or periplasmic funnels of NhaA structure. 2) Cys replacements of the conserved residues and measuring their antiporter activity in everted membr

SUBMITTER: Herz K 

PROVIDER: S-EPMC2804377 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature