title: Gating at the selectivity filter of ion channels that conduct Na+ and K+ ions.
abstract: The NaK channel is a cation selective channel with similar permeability for K(+) and Na(+). The available crystallographic structure of wild-type (WT) NaK is usually associated with a conductive state of the channel. Here, potential of mean force for complete conduction events of Na(+) and K(+) ions through NaK show that: i), large energy barriers prevent the passage of ions through the WT NaK structure, ii), the barriers are correlated to the presence of a hydrogen bond between Asp-66 and Asn-68, and iii), the structure of NaK mutated to mimic cyclic nucleotide-gated channels conducts Na(+) and K(+). These results support the hypothesis that the filter of cation selective channels can adopt at least two different structures: a conductive one, represented by the x-ray structures of the NaK-CNG chimeras, and a closed one, represented by the x-ray structures of the WT NaK.
authors.affiliation: Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Simone
authors.initials: S
authors.lastname: Furini
authors.forename: Carmen
authors.initials: C
authors.lastname: Domene
mesh_terms: D019943:Amino Acid Substitution; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D010539:Permeability; D011188:Potassium / Q000378:metabolism*; D011487:Protein Conformation; D012964:Sodium / Q000378:metabolism*; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D007473:Ion Channels; D012964:Sodium; D011188:Potassium