Discovery, Characterization, and Engineering of LvIC, an α4/4-Conotoxin That Selectively Blocks Rat α6/α3β4 Nicotinic Acetylcholine Receptors

• Published in: Journal of medicinal chemistry Vol. 66; no. 3; pp. 2020 - 2031
• Main Authors: Zhu, Xiaopeng, Wang, Shuai, Kaas, Quentin, Yu, Jinpeng, Wu, Yong, Harvey, Peta J., Zhangsun, Dongting, Craik, David J., Luo, Sulan
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.02.2023
• Subjects: Animals; Conotoxins - chemistry; Molecular Docking Simulation; Nicotinic Antagonists - chemistry; Nicotinic Antagonists - pharmacology; Oocytes; Rats; Receptors, Nicotinic - chemistry; Xenopus laevis
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.2c01786

α6β4 nicotinic acetylcholine receptors (nAChRs) are expressed in the central and peripheral nervous systems, but their functions are not fully understood, largely because of a lack of specific ligands. Here, we characterized a novel α-conotoxin, LvIC, and designed a series of analogues to probe structure–activity relationships at the α6β4 nAChR. The potency and selectivity of these conotoxins were tested using two-electrode voltage-clamp recording on nAChR subtypes expressed in Xenopus laevis oocytes. One of the analogues, [D1G,ΔQ14]­LvIC, potently blocked α6/α3β4 nAChRs (α6/α3 is a chimera) with an IC50 of 19 nM, with minimal activity at other nAChR subtypes, including the structurally similar α6/α3β2β3 and α3β4 subtypes. Using NMR, molecular docking, and receptor mutation, structure–activity relationships of [D1G,ΔQ14]­LvIC at the α6/α3β4 nAChR were defined. It is a potent and specific antagonist of α6β4 nAChRs that could potentially serve as a novel molecular probe to explore α6β4 nAChR-related neurophysiological and pharmacological functions.