title: Activation of G-protein-coupled receptors correlates with the formation of a continuous internal water pathway.
abstract: Recent crystal structures of G-protein-coupled receptors (GPCRs) have revealed ordered internal water molecules, raising questions about the functional role of those waters for receptor activation that could not be answered by the static structures. Here, we used molecular dynamics simulations to monitor--at atomic and high temporal resolution--conformational changes of central importance for the activation of three prototypical GPCRs with known crystal structures: the adenosine A2A receptor, the β2-adrenergic receptor and rhodopsin. Our simulations reveal that a hydrophobic layer of amino acid residues next to the characteristic NPxxY motif forms a gate that opens to form a continuous water channel only upon receptor activation. The highly conserved tyrosine residue Y(7.53) undergoes transitions between three distinct conformations representative of inactive, G-protein activated and GPCR metastates. Additional analysis of the available GPCR crystal structures reveals general principles governing the functional roles of internal waters in GPCRs.
authors.affiliation: 1] Laboratory of Physical Chemistry of Polymers and Membranes, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland [2] Present address: Actelion Pharmaceuticals Ltd, 4123 Basel, Switzerland.
authors.forename: Shuguang
authors.initials: S
authors.lastname: Yuan
authors.affiliation: Laboratory of Biomodeling, Faculty of Chemistry &Biological and Chemical Research Centre, University of Warsaw, 02-093 Warsaw, Poland.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Filipek
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
authors.affiliation: Laboratory of Physical Chemistry of Polymers and Membranes, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Horst
authors.initials: H
authors.lastname: Vogel
mesh_terms: D018360:Crystallography, X-Ray; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D043705:Receptor, Adenosine A2A / Q000737:chemistry* / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry*
chemical_list: D043705:Receptor, Adenosine A2A; D018343:Receptors, Adrenergic, beta-2; D043562:Receptors, G-Protein-Coupled; D014867:Water; D012243:Rhodopsin