title: Photo-switchable tweezers illuminate pore-opening motions of an ATP-gated P2X ion channel.
abstract: P2X receptors function by opening a transmembrane pore in response to extracellular ATP. Recent crystal structures solved in apo and ATP-bound states revealed molecular motions of the extracellular domain following agonist binding. However, the mechanism of pore opening still remains controversial. Here we use photo-switchable cross-linkers as 'molecular tweezers' to monitor a series of inter-residue distances in the transmembrane domain of the P2X2 receptor during activation. These experimentally based structural constraints combined with computational studies provide high-resolution models of the channel in the open and closed states. We show that the extent of the outer pore expansion is significantly reduced compared to the ATP-bound structure. Our data further reveal that the inner and outer ends of adjacent pore-lining helices come closer during opening, likely through a hinge-bending motion. These results provide new insight into the gating mechanism of P2X receptors and establish a versatile strategy applicable to other membrane proteins.
authors.affiliation: Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.|Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France.
authors.forename: Chloé
authors.initials: C
authors.lastname: Habermacher
authors.affiliation: Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.|Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Martz
authors.affiliation: ISIS, Unité Mixte de Recherche 7006, Laboratoire d'Ingénierie des Fonctions Moléculaires, Strasbourg, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Calimet
authors.affiliation: Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.|Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Lemoine
authors.affiliation: Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.|Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France.
authors.forename: Laurie
authors.initials: L
authors.lastname: Peverini
authors.affiliation: Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.|Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Specht
authors.affiliation: ISIS, Unité Mixte de Recherche 7006, Laboratoire d'Ingénierie des Fonctions Moléculaires, Strasbourg, France.
authors.forename: Marco
authors.initials: M
authors.lastname: Cecchini
authors.affiliation: Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.|Centre National de la Recherche Scientifique, Laboratoire de Conception et Application de Molécules Bioactives, Unité Mixte de Recherche 7199, Équipe de Chimie et Neurobiologie Moléculaire, Illkirch, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Grutter
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D007473:Ion Channels / Q000378:metabolism*; D008954:Models, Biological; D056004:Molecular Dynamics Simulation; D052898:Optical Tweezers; D011487:Protein Conformation; D051381:Rats; D058476:Receptors, Purinergic P2X2 / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D058476:Receptors, Purinergic P2X2; D000255:Adenosine Triphosphate
keywords: P2X receptors; azobenzene photoswitch; biophysics; gating mechanism; neuroscience; none; structural biology
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