title: Free RCK arrangement in Kch, a putative escherichia coli potassium channel, as suggested by electron crystallography.
abstract: The ligand-gated potassium channels are stimulated by various kinds of messengers. Previous studies showed that ligand-gated potassium channels containing RCK domains (the regulator of the conductance of potassium ion) form a dimer of tetramer structure through the RCK octameric gating ring in the presence of detergent. Here, we have analyzed the structure of Kch, a channel of this type from Escherichia coli, in a lipid environment using electron crystallography. By combining information from the 3D map of the transmembrane part of the protein and docking of an atomic model of a potassium channel, we conclude that the RCK domains face the solution and that an RCK octameric gating ring arrangement does not form under our crystallization condition. Our findings may be applied to other potassium channels that have an RCK gating ring arrangement.
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden. Electronic address: qie.kuang@ki.se.
authors.forename: Qie
authors.initials: Q
authors.lastname: Kuang
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden.
authors.forename: Pasi
authors.initials: P
authors.lastname: Purhonen
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden.
authors.forename: Caroline
authors.initials: C
authors.lastname: Jegerschöld
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden.
authors.forename: Philip J B
authors.initials: PJB
authors.lastname: Koeck
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden. Electronic address: hans.hebert@ki.se.
authors.forename: Hans
authors.initials: H
authors.lastname: Hebert
mesh_terms: D003461:Crystallography; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins / Q000737:chemistry*; D015640:Ion Channel Gating; D008055:Lipids / Q000494:pharmacology; D008854:Microscopy, Electron; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D015221:Potassium Channels / Q000737:chemistry*; D060066:Protein Interaction Maps; D020836:Protein Structure, Quaternary / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects
chemical_list: D029968:Escherichia coli Proteins; D008055:Lipids; D015221:Potassium Channels; C101871:kch protein, E coli