title: Transmembrane allosteric coupling of the gates in a potassium channel.
abstract: It has been hypothesized that transmembrane allostery is the basis for inactivation of the potassium channel KcsA: opening the intracellular gate is spontaneously followed by ion expulsion at the extracellular selectivity filter. This suggests a corollary: following ion expulsion at neutral pH, a spontaneous global conformation change of the transmembrane helices, similar to the motion involved in opening, is expected. Consequently, both the low potassium state and the low pH state of the system could provide useful models for the inactivated state. Unique NMR studies of full-length KcsA in hydrated bilayers provide strong evidence for such a mutual coupling across the bilayer: namely, upon removing ambient potassium ions, changes are seen in the NMR shifts of carboxylates E118 and E120 in the pH gate in the hinges of the inner transmembrane helix (98-103), and in the selectivity filter, all of which resemble changes seen upon acid-induced opening and inhibition and suggest that ion release can trigger channel helix opening.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Wylie
authors.forename: Manasi P
authors.initials: MP
authors.lastname: Bhate
authors.forename: Ann E
authors.initials: AE
authors.lastname: McDermott
mesh_terms: D000495:Allosteric Site; D001426:Bacterial Proteins / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009154:Mutation; D011188:Potassium / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry / Q000502:physiology*; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D002264:Carboxylic Acids; D008051:Lipid Bilayers; D015221:Potassium Channels; D011506:Proteins; C107790:prokaryotic potassium channel; D011188:Potassium
keywords: C-type inactivation; chemical shift assignments; membrane protein; protein dynamics; solid-state NMR