title: Unique residues in the ATP gated human P2X7 receptor define a novel allosteric binding pocket for the selective antagonist AZ10606120.
abstract: The P2X7 receptor (P2X7R) for ATP is a therapeutic target for pathophysiological states including inflammation, pain management and epilepsy. This is facilitated by the predicted low side effect profile as the high concentrations of ATP required to activate the receptor are usually only found following cell damage/disease and so P2X7Rs respond to a "danger" signal and are not normally active. AZ10606120 is a selective antagonist for P2X7Rs (IC50of ~10 nM) and ineffective at the P2X1R (at 10 μM). To determine the molecular basis of selectivity we generated a series of P2X7/1R chimeras and mutants. Two regions that are unique to the P2X7R, a loop insertion (residues 73-79) and threonine residues T90 and T94, are required for high affinity antagonist action. Point mutations ruled out an orthosteric antagonist site. Mutations and molecular modelling identified an allosteric binding site that forms at the subunit interface at the apex of the receptor. Molecular dynamics simulations indicated that unique P2X7R features regulate access of AZ10606120 to the allosteric site. The characterisation of the allosteric pocket provides a new and novel target for rational P2X7R drug development.
authors.affiliation: Department of Molecular and Cell Biology, University of Leicester, Leicester, UK.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Allsopp
authors.affiliation: Department of Molecular and Cell Biology, University of Leicester, Leicester, UK.|Department of Chemistry, College of Science, University of Baghdad, Baghdad, Iraq.
authors.forename: Sudad
authors.initials: S
authors.lastname: Dayl
authors.affiliation: Department of Molecular and Cell Biology, University of Leicester, Leicester, UK.|Leicester Institute of Structural and Chemical Biology, University of Leicester, Leicester, UK.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schmid
authors.affiliation: Department of Molecular and Cell Biology, University of Leicester, Leicester, UK. rje6@le.ac.uk.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Evans
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000483:Alleles; D000494:Allosteric Regulation; D000495:Allosteric Site; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000634:Aminoquinolines / Q000737:chemistry* / Q000494:pharmacology; D001665:Binding Sites; D006801:Humans; D015640:Ion Channel Gating; D017705:Lignans; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D058920:Purinergic P2X Receptor Antagonists / Q000737:chemistry* / Q000494:pharmacology; D058486:Receptors, Purinergic P2X7 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: C000602458:AZ10606120; D000634:Aminoquinolines; D017705:Lignans; D058920:Purinergic P2X Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D000218:Adamantane