title: Identification and functional characterization of a novel α-conotoxin (EIIA) from Conus ermineus.
abstract: Nicotinic acetylcholine receptors (nAChRs) are one of the most important families in the ligand-gated ion channel superfamily due to their involvement in primordial brain functions and in several neurodegenerative pathologies. The discovery of new ligands which can bind with high affinity and selectivity to nAChR subtypes is of prime interest in order to study these receptors and to potentially discover new drugs for treating various pathologies. Predatory cone snails of the genus Conus hunt their prey using venoms containing a large number of small, highly structured peptides called conotoxins. Conotoxins are classified in different structural families and target a large panel of receptors and ion channels. Interestingly, nAChRs represent the only subgroup for which Conus has developed seven distinct families of conotoxins. Conus venoms have thus received much attention as they could represent a potential source of selective ligands of nAChR subtypes. We describe the mass spectrometric-based approaches which led to the discovery of a novel α-conotoxin targeting muscular nAChR from the venom of Conus ermineus. The presence of several posttranslational modifications complicated the N-terminal sequencing. To discriminate between the different possible sequences, analogs with variable N-terminus were synthesized and fragmented by MS/MS. Understanding the fragmentation pathways in the low m/z range appeared crucial to determine the right sequence. The biological activity of this novel α-conotoxin (α-EIIA) that belongs to the unusual α4/4 subfamily was determined by binding experiments. The results revealed not only its selectivity for the muscular nAChR, but also a clear discrimination between the two binding sites described for this receptor.
authors.affiliation: Laboratoire des Mécanismes Réactionnels, Département de Chimie, Ecole Polytechnique, CNRS UMR7651, 91128 Palaiseau Cedex, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Quinton
authors.forename: Denis
authors.initials: D
authors.lastname: Servent
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Girard
authors.forename: Jordi
authors.initials: J
authors.lastname: Molgó
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Le Caer
authors.forename: Christian
authors.initials: C
authors.lastname: Malosse
authors.forename: El Ali
authors.initials: el A
authors.lastname: Haidar
authors.forename: Alain
authors.initials: A
authors.lastname: Lecoq
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gilles
authors.forename: Julia
authors.initials: J
authors.lastname: Chamot-Rooke
mesh_terms: D000109:Acetylcholine / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D020916:Conotoxins / Q000032:analysis* / Q000378:metabolism; D052078:Conus Snail / Q000502:physiology*; D008978:Mollusk Venoms / Q000737:chemistry*; D011485:Protein Binding; D053719:Tandem Mass Spectrometry
chemical_list: D020916:Conotoxins; D008978:Mollusk Venoms; D000109:Acetylcholine