title: Structural Basis for Differences in Dynamics Induced by Leu Versus Ile Residues in the CD Loop of Kir Channels.
abstract: The effect of the conserved Leu/Ile site in the CD loop on the gating dynamics of Kir channels and corresponding micro-structural mechanism remains unclear. Molecular dynamics simulations were performed to investigate the structural mechanism of chicken Kir2.2. Compared to WT, the I223L mutant channel bound to PIP2more strongly, was activated more rapidly, and maintained the activation state more stably after PIP2dissociation. Cellular electrophysiology assays of mouse Kir2.1 and human Kir2.2 indicated that, consistent with simulations, the Leu residue increased the channel responses to PIP2through increased binding affinity and faster activation kinetics, and the deactivation kinetics decreased upon PIP2inhibition. The Ile residue induced the opposite responses. This difference was attributed to the distinct hydrophobic side chain symmetries of Leu and Ile; switching between these residues caused the interaction network to redistribute and offered effective conformation transduction in the Leu systems, which had more rigid and independent subunits.
authors.affiliation: Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China.|Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China.|Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Shouqin
authors.initials: S
authors.lastname: Lü
authors.affiliation: Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: An
authors.affiliation: Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of Pharmacology and Toxicology for New Drug, Hebei Province, Department of Pharmacology, Hebei Medical University, Shijiazhuang, 050017, China. zhanghl@hebmu.edu.cn.
authors.forename: Hailin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Center of Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China. mlong@imech.ac.cn.|Key Laboratory of Microgravity (National Microgravity Laboratory), Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China. mlong@imech.ac.cn.|Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China. mlong@imech.ac.cn.
authors.forename: Mian
authors.initials: M
authors.lastname: Long
mesh_terms: D000818:Animals; D002645:Chickens; D003198:Computer Simulation; D006801:Humans; D015640:Ion Channel Gating; D007532:Isoleucine / Q000235:genetics*; D007700:Kinetics; D007930:Leucine / Q000235:genetics*; D051379:Mice; D009154:Mutation / Q000235:genetics; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry* / Q000235:genetics; D060066:Protein Interaction Maps; D017433:Protein Structure, Secondary; D014981:Xenopus
chemical_list: C489461:Kir2.1 channel; C489463:Kir2.2 channel; D019269:Phosphatidylinositol 4,5-Diphosphate; D024661:Potassium Channels, Inwardly Rectifying; D007532:Isoleucine; D007930:Leucine
keywords: Conformational change; Inward-rectifier potassium channel; Molecular dynamics simulations; Patch clamp; Structure-function relationship