Structure and Dynamics of Membrane-embedded KcsA Potassium Channel Revealed by Atomic Force Microscopy

Abstract

The KcsA channel is a prototypical potassium channel, exhibiting pH-dependent gating. The structure of the transmembrane pore-domain of the KcsA channel was examined using atomic force microscopy (AFM) under the membrane-embedded condition. In the closed conformation, the cytoplasmic end of the pore domain was protruded from the membrane surface. In the open conformation, the open pore at the center of the tetrameric channel was resolved, and the protrusion was substantially shortened relative to the closed conformation. High-speed AFM revealed the clustering–dispersion dynamics upon pH changes, and this collective behavior was closely related to the gating conformational changes.