Discovery and Structural and Functional Characterization of a Novel A-Superfamily Conotoxin Targeting α9α10 Nicotinic Acetylcholine Receptor

Abstract

Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels widely distributed in the central peripheral nervous system and muscles which participate in rapid synaptic transmission. The α9α10 nAChR is an acetylcholine receptor subtype and is involved in chronic pain. In the present study, a new A-superfamily conotoxin Bt14.12 cloned from Conus betulinus was found to selectively inhibit α9α10 nAChRs with an IC 50 of 62.3 nM. Unlike α-conotoxins and other Asuperfamily conotoxins, Bt14.12 contains a four Cys (C−C−C−C) framework with a unique disulfide bond connection "C1−C4, C2−C3". The structure−activity studies of Bt14.12 demonstrate that all amino acid residues contribute to its potency. Interestingly, mutation experiments show that the deletion of Asp 2 or the addition of three Arg residues at the N-terminus of Bt14.12 significantly enhances its inhibitory activity (IC 50 is 21.9 nM or 12.7 nM, respectively) by 2-or 4-fold compared to the wild-type Bt14.12. The NMR structure of Bt14.12 shows that it contains α-helixand β-turn-like elements, and further computational modelings of the interaction between Bt14.12 and the α9α10 nAChR demonstrate that Bt14.12 possesses a distinctive mode of action and displays a different structure−activity relationship from known α9α10 nAChR targeting α-conotoxins. Our findings provide a novel conotoxin that potently targets α9α10 nAChRs and a new motif for designing potent inhibitors against α9α10 nAChRs.

The human alpha7 nicotinic acetylcholine receptor is a host target for the rabies virus glycoprotein

“…Conotoxins are well-studied short peptides (12 - 40 amino acids) that target nAChRs with subtype specificity. Using single point substitutions outside of the predicted interaction region and comparison to the unmutated conotoxin are used as a control for these peptides ( Hone et al., 2019 ; Huang et al., 2022 ; Xu et al., 2023 ). In our presented work, residue S195 in the RVG peptide has been substituted with an A and the effects on the apparent potency have been evaluated.…”

α7- and α9-Containing Nicotinic Acetylcholine Receptors in the Functioning of Immune System and in Pain

“…In the case of conotoxins, lyophilization or encapsulation in microspheres could diminish their intrinsic instability and provide a sustained release of the drug to meet the clinical treatment needs of chronic pain [ 207 , 233 ]. In addition, new small-molecules [ 182 , 234 ] and peptide [ 235 ] inhibitors of α9-containing nAChRs are emerging, differing in chemical structure from known analogs. For example, a new A-superfamily conotoxin Bt14.12, similar to α-conotoxins and other A-superfamily conotoxins, contains a four Cys (C-C-C-C) framework, but with a unique disulfide bond connection “C1-C4, C2-C3”.…”

Novel Triazole‐Containing “Dipeptides”: Synthesis, Molecular Docking and Analgesic Activity Studies

“…Neuronal nicotinic acetylcholine receptors (nAChRs) (Figure 1) are prototypical cation‐selective, ligand‐gated ion channels that mediate fast neurotransmission in the central and peripheral nervous systems. nAChRs are involved in a range of physiological and pathological functions and hence are important therapeutic targets [1a,b] …”

“…A wide spectrum of action of triazole derivatives, on the one hand, and neuropathic pain as one of the unresolved and urgent problems of modern medicine, on the other hand, became a prerequisite for further study of antinociceptive activity [1a,b] . The choice of nAChR receptors as a potential target for the obtained compounds was due to their structure, the analysis of which revealed the presence of possible pharmacophore groups for binding to the selected receptor.…”