title: Marine Macrocyclic Imines, Pinnatoxins A and G: Structural Determinants and Functional Properties to Distinguish Neuronal α7 from Muscle α1(2)βγδ nAChRs.
abstract: Pinnatoxins are macrocyclic imine phycotoxins associated with algal blooms and shellfish toxicity. Functional analysis of pinnatoxin A and pinnatoxin G by binding and voltage-clamp electrophysiology on membrane-embedded neuronal α7, α4β2, α3β2, and muscle-type α12βγδ nicotinic acetylcholine receptors (nAChRs) reveals high-affinity binding and potent antagonism for the α7 and α12βγδ subtypes. The toxins also bind to the nAChR surrogate, acetylcholine-binding protein (AChBP), with low Kd values reflecting slow dissociation. Crystal structures of pinnatoxin-AChBP complexes (1.9-2.2 Å resolution) show the multiple anchoring points of the hydrophobic portion, the cyclic imine, and the substituted bis-spiroketal and cyclohexene ring systems of the pinnatoxins that dictate tight binding between the opposing loops C and F at the receptor subunit interface, as observed for the 13-desmethyl-spirolide C and gymnodimine A congeners. Uniquely, however, the bulky bridged EF-ketal ring specific to the pinnatoxins extends radially from the interfacial-binding pocket to interact with the sequence-variable loop F and govern nAChR subtype selectivity and central neurotoxicity.
authors.affiliation: Aix-Marseille Université, Laboratoire Architecture et Fonction des Macromolécules Biologiques, Campus Luminy, 13288 Marseille cedex 9, France; Centre National de la Recherche Scientifique, Laboratoire Architecture et Fonction des Macromolécules Biologiques, Campus Luminy, 13288 Marseille cedex 9, France. Electronic address: yves.bourne@afmb.univ-mrs.fr.
authors.forename: Yves
authors.initials: Y
authors.lastname: Bourne
authors.affiliation: Aix-Marseille Université, Laboratoire Architecture et Fonction des Macromolécules Biologiques, Campus Luminy, 13288 Marseille cedex 9, France; Centre National de la Recherche Scientifique, Laboratoire Architecture et Fonction des Macromolécules Biologiques, Campus Luminy, 13288 Marseille cedex 9, France.
authors.forename: Gerlind
authors.initials: G
authors.lastname: Sulzenbacher
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093-0650, USA.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Radić
authors.affiliation: Institut des Neurosciences Paris-Saclay, Centre National de la Recherche Scientifique, 91190 Gif-sur-Yvette, France; Commissariat à l'Energie Atomique, iBiTecS, Service d'Ingénierie Moléculaire des Protéines, 91191 Gif-sur-Yvette, France.
authors.forename: Rómulo
authors.initials: R
authors.lastname: Aráoz
authors.affiliation: Commissariat à l'Energie Atomique, iBiTecS, Service d'Ingénierie Moléculaire des Protéines, 91191 Gif-sur-Yvette, France.
authors.forename: Morgane
authors.initials: M
authors.lastname: Reynaud
authors.affiliation: Institut des Neurosciences Paris-Saclay, Centre National de la Recherche Scientifique, 91190 Gif-sur-Yvette, France; Commissariat à l'Energie Atomique, iBiTecS, Service d'Ingénierie Moléculaire des Protéines, 91191 Gif-sur-Yvette, France.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Benoit
authors.affiliation: Department of Chemistry and Biochemistry, University of California Santa Barbara, CA 93106-9510, USA.
authors.forename: Armen
authors.initials: A
authors.lastname: Zakarian
authors.affiliation: Commissariat à l'Energie Atomique, iBiTecS, Service d'Ingénierie Moléculaire des Protéines, 91191 Gif-sur-Yvette, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Servent
authors.affiliation: Institut des Neurosciences Paris-Saclay, Centre National de la Recherche Scientifique, 91190 Gif-sur-Yvette, France; Commissariat à l'Energie Atomique, iBiTecS, Service d'Ingénierie Moléculaire des Protéines, 91191 Gif-sur-Yvette, France.
authors.forename: Jordi
authors.initials: J
authors.lastname: Molgó
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093-0650, USA.
authors.forename: Palmer
authors.initials: P
authors.lastname: Taylor
authors.affiliation: Aix-Marseille Université, Laboratoire Architecture et Fonction des Macromolécules Biologiques, Campus Luminy, 13288 Marseille cedex 9, France; Centre National de la Recherche Scientifique, Laboratoire Architecture et Fonction des Macromolécules Biologiques, Campus Luminy, 13288 Marseille cedex 9, France. Electronic address: pascale.marchot@univ-amu.fr.
authors.forename: Pascale
authors.initials: P
authors.lastname: Marchot
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D007097:Imines / Q000737:chemistry*; D007700:Kinetics; D047028:Macrocyclic Compounds / Q000737:chemistry*; D008387:Marine Toxins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D018408:Patch-Clamp Techniques; D011485:Protein Binding; D011487:Protein Conformation; D011978:Receptors, Nicotinic / Q000378:metabolism; D013141:Spiro Compounds / Q000737:chemistry*; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C428944:AChBP protein, Lymnaea; D000470:Alkaloids; D002352:Carrier Proteins; D007097:Imines; D047028:Macrocyclic Compounds; D008387:Marine Toxins; D011978:Receptors, Nicotinic; D013141:Spiro Compounds; C000591196:alpha1beta1gammadelta receptor, human; D064569:alpha7 Nicotinic Acetylcholine Receptor; C419362:nicotinic receptor alpha3beta2; C403531:nicotinic receptor alpha4beta2; C447983:pinnatoxin A; C552840:pinnatoxin G