Effects of the Protonation State of the EEEE Motif of a Bacterial Na+-channel on Conduction and Pore Structure

A distinctive feature of prokaryotic Na+-channels is the presence of four glutamate residues in their selectivity filter. In this study, how the structure of the selectivity filter, and the free-energy profile of permeating Na+ ions are altered by the protonation state of Glu177 are analyzed. It was found that protonation of a single glutamate residue was enough to modify the conformation of the selectivity filter and its conduction properties....