AChBP-targeted alpha-conotoxin correlates distinct binding orientations with nAChR subtype selectivity

  • Neuronal nAChRs are a diverse family of pentameric ion channels with wide distribution throughout cells of the nervous and immune systems. However, the role of specific subtypes in normal and pathological states remains poorly understood due to the lack of selective probes. Here, we used a binding assay based on acetylcholine-binding protein (AChBP), a homolog of the nicotinic acetylcholine ligand-binding domain, to discover a novel alpha-conotoxin (alpha-TxIA) in the venom of Conus textile. alpha-TxIA bound with high affinity to AChBPs from different species and selectively targeted the alpha3beta2 nAChR subtype. A co-crystal structure of Ac-AChBP with the enhanced potency analog TxIA(A10L), revealed a 20° backbone tilt compared to other AChBP–conotoxin complexes. This reorientation was coordinated by a key salt bridge formed between Arg5 (TxIA) and Asp195 (Ac-AChBP). Mutagenesis studies, biochemical assays and electrophysiological recordings directly correlated the interactions observed in the co-crystal structure to binding affinity at AChBP and different nAChR subtypes. Together, these results establish a new pharmacophore for the design of novel subtype-selective ligands with therapeutic potential in nAChR-related diseases.

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Author:Sébastien Dutertre, Chris Ulens, Regina Büttner, Alexander Fish, René van Elk, Yvonne Kendel, Gene Hopping, Paul F. Alewood, Christina Schroeder, Annette Nicke, August B. Smit, Titia K. Sixma, Richard J. Lewis
Pubmed Id:
Parent Title (English):The EMBO journal
Publisher:Nature Publ. Group
Place of publication:London [u. a.]
Document Type:Article
Year of Completion:2007
Date of first Publication:2007/07/26
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2009/10/08
Tag:acetylcholine binding protein; conotoxin; cys-loop receptor; ion channel; nicotinic acetylcholine receptors
Page Number:10
First Page:3858
Last Page:3867
This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
Source:The EMBO Journal (2007) 26, No. 16, 3858–3867 ; doi:10.1038/sj.emboj.7601785 ;
Institutes:Medizin / Medizin
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Sammlungen:Sammlung Biologie / Sondersammelgebiets-Volltexte
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell-Keine Bearbeitung 3.0