Hydration of Conduction Pores in KcsA Potassium Channel and M2 Proton Channel

Published

September 14, 2015

Author(s)

J L. Blasic, David L. Worcester, Klaus Gawrisch, Philip A. Gurnev, Mihaela Mihailescu

Abstract

Water-filled hydrophobic cavities of channel proteins serve as gateways for transfer of ions across membrane. However, functional implications of hydration-dehydration transitions remain elusive due to difficulties to detect and quantify water in channel cavities. Here we employ neutron diffraction to determine water distributions in two tetrameric channels embedded in lipid bilayers: potassium channel KcsA and trans-membrane domain of M2 protein of Influenza A virus. We show that for the KcsA channel in the closed state, the distribution of water is peaked in the middle of the membrane, showing water in the central cavity. This water is displaced by the channel blocker tetrabutyl-ammonium. We quantify amounts of water associated with the channel, using neutron diffraction and solid-state NMR. In contrast, the M2 proton channel shows a "V"- shaped water profile across the membrane, with a narrow constriction at the center, like the hour-glass shape of its internal surface.

Citation

Journal of Biological Chemistry

Volume

290

Issue

44

Pub Type

Journals

Download Paper

DOI Link

Keywords

lipid bilayer, neutron diffraction, ion channels, KcsA, M2

Citation

Blasic, J. , Duewer, D. , Gawrisch, K. , , P. and Mihailescu, M. (2015), Hydration of Conduction Pores in KcsA Potassium Channel and M2 Proton Channel, Journal of Biological Chemistry, [online], https://doi.org/10.1074/jbc.M115.661819 (Accessed October 16, 2025)