title: Global twisting motion of single molecular KcsA potassium channel upon gating.
abstract: 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.
authors.affiliation: CREST Sasaki-team, Japan Science and Technology Corporation, Tachikawa, Tokyo, 190-0012, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Shimizu
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iwamoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Konno
authors.forename: Amiko
authors.initials: A
authors.lastname: Nihei
authors.forename: Yuji C
authors.initials: YC
authors.lastname: Sasaki
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Oiki
mesh_terms: 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
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; C107790:prokaryotic potassium channel