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  • The EMBO Journal (2007) 26, 3858 - 3867
  • doi:10.1038/sj.emboj.7601785

Published online: 26 July 2007

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

Sébastien Dutertre1,ab, Chris Ulens2,a, Regina Büttner3, Alexander Fish2, René van Elk4, Yvonne Kendel5, Gene Hopping1, Paul F Alewood1, Christina Schroeder1, Annette Nicke3, August B Smit4, Titia K Sixma2 and Richard J Lewis1

  1. Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
  2. Division of Molecular Carcinogenesis and Center for Biomedical Genetics, Netherlands Cancer Institute, Plesmanlaan, CX Amsterdam, The Netherlands
  3. Department of Neurochemistry, Max Planck Institute for Brain Research, Deutschordenstrasse 46, Frankfurt am Main, Germany
  4. Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, The Netherlands
  5. Zentrum der Rechtsmedizin, University of Frankfurt, Frankfurt am Main, Germany

Correspondence to:

Richard J Lewis, Institute for Molecular Bioscience, The University of Queensland, Carmodty Rd, Brisbane, Queensland 4072, Australia. Tel.: +617 3346 2984; Fax: +617 3346 2101; E-mail: r.lewis@imb.uq.edu.au

Titia K Sixma, Division of Molecular Carcinogenesis and Center for Biomedical Genetics, Netherlands Cancer Institute, Plesmanlaan, 1066 CX Amsterdam, The Netherlands. E-mail: t.sixma@nki.nl

aThese authors contributed equally to this work

bPresent address: Max Planck Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany.

Received 6 February 2007; Accepted 12 June 2007

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.

  • Keywords:

    • acetylcholine binding protein,
    • conotoxin,
    • cys-loop receptor,
    • ion channel,
    • nicotinic acetylcholine receptors

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The EMBO Journal is published by Nature Publishing Group on behalf of European Molecular Biology Organization