| Structural highlights
Function
[CA1D_CONGE] Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. This toxin reversibly blocks alpha-3-beta-2 (IC(50)=3.1-5.1 nM), alpha-7 (IC(50)=4.5-5.1 nM), and alpha-4-beta-2 (IC(50)=128.6-390 nM) nAChRs.[1] [2] [3]
Publication Abstract from PubMed
Venom peptide toxins such as conotoxins play a critical role in the characterization of nicotinic acetylcholine receptor (nAChR) structure and function and have potential as nervous system therapeutics as well. However, the lack of solved structures of conotoxins bound to nAChRs and the large size of these peptides are barriers to their computational docking and design. We addressed these challenges in the context of the alpha4beta2 nAChR, a widespread ligand-gated ion channel in the brain and a target for nicotine addiction therapy, and the 19-residue conotoxin alpha-GID that antagonizes it. We developed a docking algorithm, ToxDock, which used ensemble-docking and extensive conformational sampling to dock alpha-GID and its analogs to an alpha4beta2 nAChR homology model. Experimental testing demonstrated that a virtual screen with ToxDock correctly identified three bioactive alpha-GID mutants (alpha-GID[A10V], alpha-GID[V13I], and alpha-GID[V13Y]) and one inactive variant (alpha-GID[A10Q]). Two mutants, alpha-GID[A10V] and alpha-GID[V13Y], had substantially reduced potency at the human alpha7 nAChR relative to alpha-GID, a desirable feature for alpha-GID analogs. The general usefulness of the docking algorithm was highlighted by redocking of peptide toxins to two ion channels and a binding protein in which the peptide toxins successfully reverted back to near-native crystallographic poses after being perturbed. Our results demonstrate that ToxDock can overcome two fundamental challenges of docking large toxin peptides to ion channel homology models, as exemplified by the alpha-GID:alpha4beta2 nAChR complex, and is extendable to other toxin peptides and ion channels. ToxDock is freely available at rosie.rosettacommons.org/tox_dock.
Discovery of peptide ligands through docking and virtual screening at nicotinic acetylcholine receptor homology models.,Leffler AE, Kuryatov A, Zebroski HA, Powell SR, Filipenko P, Hussein AK, Gorson J, Heizmann A, Lyskov S, Tsien RW, Poget SF, Nicke A, Lindstrom J, Rudy B, Bonneau R, Holford M Proc Natl Acad Sci U S A. 2017 Sep 19;114(38):E8100-E8109. doi:, 10.1073/pnas.1703952114. Epub 2017 Sep 5. PMID:28874590[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Nicke A, Loughnan ML, Millard EL, Alewood PF, Adams DJ, Daly NL, Craik DJ, Lewis RJ. Isolation, structure, and activity of GID, a novel alpha 4/7-conotoxin with an extended N-terminal sequence. J Biol Chem. 2003 Jan 31;278(5):3137-44. Epub 2002 Nov 4. PMID:12419800 doi:http://dx.doi.org/10.1074/jbc.M210280200
- ↑ Dutertre S, Nicke A, Lewis RJ. Beta2 subunit contribution to 4/7 alpha-conotoxin binding to the nicotinic acetylcholine receptor. J Biol Chem. 2005 Aug 26;280(34):30460-8. Epub 2005 Jun 1. PMID:15929983 doi:http://dx.doi.org/10.1074/jbc.M504229200
- ↑ Millard EL, Nevin ST, Loughnan ML, Nicke A, Clark RJ, Alewood PF, Lewis RJ, Adams DJ, Craik DJ, Daly NL. Inhibition of neuronal nicotinic acetylcholine receptor subtypes by alpha-Conotoxin GID and analogues. J Biol Chem. 2009 Feb 20;284(8):4944-51. doi: 10.1074/jbc.M804950200. Epub 2008, Dec 19. PMID:19098004 doi:http://dx.doi.org/10.1074/jbc.M804950200
- ↑ Leffler AE, Kuryatov A, Zebroski HA, Powell SR, Filipenko P, Hussein AK, Gorson J, Heizmann A, Lyskov S, Tsien RW, Poget SF, Nicke A, Lindstrom J, Rudy B, Bonneau R, Holford M. Discovery of peptide ligands through docking and virtual screening at nicotinic acetylcholine receptor homology models. Proc Natl Acad Sci U S A. 2017 Sep 19;114(38):E8100-E8109. doi:, 10.1073/pnas.1703952114. Epub 2017 Sep 5. PMID:28874590 doi:http://dx.doi.org/10.1073/pnas.1703952114
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