Global twisting motion of single molecular KcsA potassium channel upon gating.
Ion channels are signal transduction molecules that switch ion permeation pathways on and off (gating). Crystal structures of several kinds of potassium channels have revealed open and closed conformations, which provide static pictures of gating status. Here we studied KcsA potassium channels undergoing conformational changes at the single-molecule level. A KcsA channel with a gold nanocrystal attached was irradiated by white X-rays and motions of the diffraction spot from the nanocrystal were tracked in real time. Upon gating, the KcsA channels twisted around the axis of the pore. These conformational changes were prevented by an open-channel blocker, tetrabuthylammonium. Random clockwise and counterclockwise twisting in the range of several tens of degrees originated in the transmembrane domain and was transmitted to the cytoplasmic domain. This coupling suggests a mechanical interplay between the transmembrane and cytoplasmic domains.
Shimizu
Hirofumi
H
CREST Sasaki-team, Japan Science and Technology Corporation, Tachikawa, Tokyo, 190-0012, Japan.
Iwamoto
Masayuki
M
Konno
Takashi
T
Nihei
Amiko
A
Sasaki
Yuji C
YC
Oiki
Shigetoshi
S
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology; D055592:Biophysical Phenomena; D001703:Biophysics; D002462:Cell Membrane / Q000737:chemistry* / Q000502:physiology; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000737:chemistry; D015640:Ion Channel Gating / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D008958:Models, Molecular; D016062:Porosity; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology; D020539:Sequence Analysis, Protein; D015398:Signal Transduction / Q000502:physiology; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D015221:Potassium Channels; C107790:prokaryotic potassium channel