title: Solution structure of ADO1, a toxin extracted from the saliva of the assassin bug, Agriosphodrus dohrni.
abstract: ADO1 is a toxin purified from the saliva of the assassin bug, Agriosphodrus dohrni. Because of its similarity in sequence to Ptu1 from another assassin bug, we did not assess its pharmacologic target. Here, we demonstrate by electrophysiologic means that ADO1 targets the P/Q-type voltage-sensitive calcium channel. We also determine the solution structure of ADO1 using two-dimensional NMR techniques, followed by distance geometry and molecular dynamics. The structure of ADO1 belongs to the inhibitory cystine knot (ICK) structural family (i.e., a compact disulfide-bonded core from which four loops emerge). ADO1 contains a two-stranded, antiparallel beta-sheet structure. We compare the structure of ADO1 with other voltage-sensitive calcium-channel blockers, analyze the topologic juxtaposition of key functional residues, and conclude that the recognition of voltage-sensitive calcium channels by toxins belonging to the ICK structural family requires residues located on two distinct areas of the molecular surface of the toxins.
authors.affiliation: Architecture et Fonction des Macromolécules Biologiques, UMR 6098, CNRS and Universités d'Aix-Marseille I and II, Marseille, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Bernard
authors.forename: Gerardo
authors.initials: G
authors.lastname: Corzo
authors.forename: Satomi
authors.initials: S
authors.lastname: Adachi-Akahane
authors.forename: Guillaume
authors.initials: G
authors.lastname: Foures
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kanemaru
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Furukawa
authors.forename: Terumi
authors.initials: T
authors.lastname: Nakajima
authors.forename: Hervé
authors.initials: H
authors.lastname: Darbon
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D004220:Disulfides / Q000737:chemistry; D004594:Electrophysiology; D019476:Insect Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D018408:Patch-Clamp Techniques; D017433:Protein Structure, Secondary; D020064:Reduviidae / Q000737:chemistry*; D012463:Saliva / Q000737:chemistry*; D013379:Substrate Specificity; D014118:Toxins, Biological / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D004220:Disulfides; D019476:Insect Proteins; D014118:Toxins, Biological; D002118:Calcium