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  • 1
    Publication Date: 2012-04-14
    Description: The mechanism of ion channel voltage gating-how channels open and close in response to voltage changes-has been debated since Hodgkin and Huxley's seminal discovery that the crux of nerve conduction is ion flow across cellular membranes. Using all-atom molecular dynamics simulations, we show how a voltage-gated potassium channel (KV) switches between activated and deactivated states. On deactivation, pore hydrophobic collapse rapidly halts ion flow. Subsequent voltage-sensing domain (VSD) relaxation, including inward, 15-angstrom S4-helix motion, completes the transition. On activation, outward S4 motion tightens the VSD-pore linker, perturbing linker-S6-helix packing. Fluctuations allow water, then potassium ions, to reenter the pore; linker-S6 repacking stabilizes the open pore. We propose a mechanistic model for the sodium/potassium/calcium voltage-gated ion channel superfamily that reconciles apparently conflicting experimental data.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jensen, Morten O -- Jogini, Vishwanath -- Borhani, David W -- Leffler, Abba E -- Dror, Ron O -- Shaw, David E -- New York, N.Y. -- Science. 2012 Apr 13;336(6078):229-33. doi: 10.1126/science.1216533.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉D E Shaw Research, New York, NY 10036, USA. morten.jensen@DEShawResearch.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22499946" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Hydrophobic and Hydrophilic Interactions ; *Ion Channel Gating ; Kv1.2 Potassium Channel/*chemistry/*metabolism ; Membrane Potentials ; Models, Biological ; Models, Molecular ; Molecular Dynamics Simulation ; Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Rats ; Recombinant Fusion Proteins/chemistry/metabolism ; Shab Potassium Channels/*chemistry/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2011-01-14
    Description: G-protein-coupled receptors (GPCRs) are eukaryotic integral membrane proteins that modulate biological function by initiating cellular signalling in response to chemically diverse agonists. Despite recent progress in the structural biology of GPCRs, the molecular basis for agonist binding and allosteric modulation of these proteins is poorly understood. Structural knowledge of agonist-bound states is essential for deciphering the mechanism of receptor activation, and for structure-guided design and optimization of ligands. However, the crystallization of agonist-bound GPCRs has been hampered by modest affinities and rapid off-rates of available agonists. Using the inactive structure of the human beta(2) adrenergic receptor (beta(2)AR) as a guide, we designed a beta(2)AR agonist that can be covalently tethered to a specific site on the receptor through a disulphide bond. The covalent beta(2)AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound beta(2)AR-T4L fusion protein in lipid bilayers through the use of the lipidic mesophase method, and determined its structure at 3.5 A resolution. A comparison to the inactive structure and an antibody-stabilized active structure (companion paper) shows how binding events at both the extracellular and intracellular surfaces are required to stabilize an active conformation of the receptor. The structures are in agreement with long-timescale (up to 30 mus) molecular dynamics simulations showing that an agonist-bound active conformation spontaneously relaxes to an inactive-like conformation in the absence of a G protein or stabilizing antibody.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074335/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074335/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rosenbaum, Daniel M -- Zhang, Cheng -- Lyons, Joseph A -- Holl, Ralph -- Aragao, David -- Arlow, Daniel H -- Rasmussen, Soren G F -- Choi, Hee-Jung -- Devree, Brian T -- Sunahara, Roger K -- Chae, Pil Seok -- Gellman, Samuel H -- Dror, Ron O -- Shaw, David E -- Weis, William I -- Caffrey, Martin -- Gmeiner, Peter -- Kobilka, Brian K -- 50GM073210/GM/NIGMS NIH HHS/ -- GM56169/GM/NIGMS NIH HHS/ -- GM75915/GM/NIGMS NIH HHS/ -- M083118/PHS HHS/ -- NS028471/NS/NINDS NIH HHS/ -- P01 GM75913/GM/NIGMS NIH HHS/ -- P60DK-20572/DK/NIDDK NIH HHS/ -- R01 GM068603/GM/NIGMS NIH HHS/ -- R37 NS028471/NS/NINDS NIH HHS/ -- R37 NS028471-20/NS/NINDS NIH HHS/ -- England -- Nature. 2011 Jan 13;469(7329):236-40. doi: 10.1038/nature09665.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, California 94305, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21228876" target="_blank"〉PubMed〈/a〉
    Keywords: Adrenergic beta-2 Receptor Agonists/*chemistry/*metabolism ; Crystallization ; Crystallography, X-Ray ; Disulfides/chemistry/metabolism ; Drug Inverse Agonism ; Heterotrimeric GTP-Binding Proteins/metabolism ; Humans ; Lipid Bilayers/chemistry/metabolism ; Models, Molecular ; Molecular Dynamics Simulation ; Procaterol/chemistry/metabolism ; Propanolamines/chemistry/metabolism ; Protein Conformation ; Receptors, Adrenergic, beta-2/*chemistry/*metabolism ; Recombinant Fusion Proteins/chemistry/metabolism ; Viral Proteins/chemistry/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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