Gating-Associated Clustering-Dispersion Dynamics of the KcsA Potassium Channel in a Lipid Membrane.
The KcsA potassium channel is a prototypical channel of bacterial origin, and the mechanism underlying the pH-dependent gating has been studied extensively. With the high-resolution atomic force microscopy (AFM), we have resolved functional open and closed gates of the KcsA channel under the membrane-embedded condition. Here we surprisingly found that the pH-dependent gating of the KcsA channels was associated with clustering-dispersion dynamics. At neutral pH, the resting, closed channels were coalesced, forming nanoclusters. At acidic pH, the open-gated channels were dispersed as singly isolated channels. Time-lapse AFM revealed reversible clustering-dispersion transitions upon pH changes. At acidic equilibrium, a small fraction of the channels was nanoclustered, in which the gate was apparently closed. Thus, it is suggested that opening of the gate and the dispersion are tightly linked. The interplay between the intramolecular conformational change and the supramolecular clustering-dispersion dynamics provides insights into understanding of unprecedented functional cooperativity of channels.
†PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi-shi, Saitama 332-0012, Japan.|‡Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Yoshida-gun, Fukui 910-1193, Japan.
Ayumi
A
Sumino
§Department of Applied Physics, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
Daisuke
D
Yamamoto
‡Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Yoshida-gun, Fukui 910-1193, Japan.
Masayuki
M
Iwamoto
∥Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
Takehisa
T
Dewa
‡Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuokashimoaizuki, Yoshida-gun, Fukui 910-1193, Japan.
Shigetoshi
S
Oiki
atomic force microscopy; clustering−dispersion; gating; nanocluster; potassium channel