title: A novel α4/7-conotoxin LvIA from Conus lividus that selectively blocks α3β2 vs. α6/α3β2β3 nicotinic acetylcholine receptors.
abstract: This study was performed to discover and characterize the first potent α3β2-subtype-selective nicotinic acetylcholine receptor (nAChR) ligand. A novel α4/7-conotoxin, α-CTxLvIA, was cloned from Conus lividus. Its pharmacological profile at Xenopus laevis oocyte-expressed rat nAChR subtypes was determined by 2-electrode voltage-clamp electrophysiology, and its 3-dimensional (3D) structure was determined by NMR spectroscopy. α-CTx LvIA is a 16-aa C-terminally-amidated peptide with 2-disulfide bridges. Using rat subunits expressed in Xenopus oocytes, we found the highest affinity of α-CTxLvIA was for α3β2 nAChRs (IC50 8.7 nM), where blockade was reversible within 2 min. IC50 values were >100 nM at α6/α3β2β3, α6/α3β4, and α3β4 nAChRs, and ≥3 μM at all other subtypes tested. α3β2 vs. α6β2 subtype selectivity was confirmed for human-subunit nAChRs with much greater preference (300-fold) for α3β2 over α6β2 nAChRs. This is the first α-CTx reported to show high selectivity for human α3β2 vs. α6β2 nAChRs. α-CTxLvIA adopts two similarly populated conformations water: one (assumed to be bioactive) is highly structured, whereas the other is mostly random coil in nature. Selectivity differences with the similarly potent, but less selective, α3β2 nAChR antagonist α-CTx PeIA probably reside within the three residues, which differ in loop 2, given their otherwise similar 3D structures. α4/7-CTx LvIA is a new, potent, selective α3β2 nAChR antagonist, which will enable detailed studies of α3β2 nAChR structure, function, and physiological roles.
authors.affiliation: 1Key Laboratory of Tropical Biological Resources, Ministry of Education, Hainan University; Haikou, Hainan, 570228 China. luosulan2003@163.com.
authors.forename: Sulan
authors.initials: S
authors.lastname: Luo
authors.forename: Dongting
authors.initials: D
authors.lastname: Zhangsun
authors.forename: Christina I
authors.initials: CI
authors.lastname: Schroeder
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Zhu
authors.forename: Yuanyan
authors.initials: Y
authors.lastname: Hu
authors.forename: Yong
authors.initials: Y
authors.lastname: Wu
authors.forename: Maegan M
authors.initials: MM
authors.lastname: Weltzin
authors.forename: Spencer
authors.initials: S
authors.lastname: Eberhard
authors.forename: Quentin
authors.initials: Q
authors.lastname: Kaas
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
authors.forename: J Michael
authors.initials: JM
authors.lastname: McIntosh
authors.forename: Paul
authors.initials: P
authors.lastname: Whiteaker
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D018679:Cholinergic Agonists / Q000494:pharmacology; D020916:Conotoxins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D052078:Conus Snail / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018733:Nicotinic Antagonists / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000295:instrumentation / Q000379:methods; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D000109:Acetylcholine; D018679:Cholinergic Agonists; D020916:Conotoxins; D018733:Nicotinic Antagonists; D011978:Receptors, Nicotinic; C419362:nicotinic receptor alpha3beta2; C104518:nicotinic receptor alpha6; C509815:nicotinic receptor beta3, rat
keywords: cholinergic; ligand-gated ion channel receptor; molecular modeling; nuclear magnetic resonance spectroscopy