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Crystal structure of the extracellular domain of nAChR α1 bound to α-bungarotoxin at 1.94 Å resolution

An Erratum to this article was published on 01 September 2007

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Abstract

We determined the crystal structure of the extracellular domain of the mouse nicotinic acetylcholine receptor (nAChR) α1 subunit bound to α-bungarotoxin at 1.94 Å resolution. This structure is the first atomic-resolution view of a nAChR subunit extracellular domain, revealing receptor-specific features such as the main immunogenic region (MIR), the signature Cys-loop and the N-linked carbohydrate chain. The toxin binds to the receptor through extensive protein-protein and protein-sugar interactions. To our surprise, the structure showed a well-ordered water molecule and two hydrophilic residues deep in the core of the α1 subunit. The two hydrophilic core residues are highly conserved in nAChRs, but correspond to hydrophobic residues in the nonchannel homolog acetylcholine-binding proteins. We carried out site-directed mutagenesis and electrophysiology analyses to assess the functional role of the glycosylation and the hydrophilic core residues. Our structural and functional studies show essential features of the nAChR and provide new insights into the gating mechanism.

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Figure 1: Overall structure of the mouse nAChR α1 subunit (cyan) bound to α-Btx (orange).
Figure 2: Structural comparison between α211, Torpedo nAChR and AChBP.
Figure 3: Binding of α-bungarotoxin to α211.
Figure 4: Structure of the MIR and the Cys-loop.
Figure 5: Structure of the carbohydrate chain and its interaction with the receptor.
Figure 6: The effect of N-linked glycosylation on the electrophysiological properties of nAChRs.
Figure 7: Mapping functional residues on the structure.
Figure 8: Electrophysiological properties of mutant nAChRs on the surface of transiently transfected COS cells.

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  • 02 August 2007

    RSCB code was omitted

Notes

  1. *NOTE: In the version of this article initially published, the RCSB Protein Database accession code for the crystal structure was omitted. At the end of the first paragraph in the Methods section, the following sentence should have been included: “The coordinates for this crystal structure have been deposited in the RCSB Protein Database under the accession code 2QC1.” The error has been corrected in the HTML and PDF versions of the article.

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Acknowledgements

The authors thank Z. Hall for encouragement, J. Anglister for sharing results of the nuclear magnetic resonance experiments and advice, H. Lester and D. Dougherty for discussions, and X. Chen and E. Liman for critical reading of the manuscript. This research was supported by grants from Muscular Dystrophy Association (Z.Z.W.) and the US National Institutes of Health (L.C. and Z.Z.W.).

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C.D.D. purified and crystallized the α211/α-Btx complex, collected X-ray diffraction data, solved and interpreted the structure, and wrote the manuscript together with L.C. Y.Y. carried out the mutational library screening, expressed and purified α211, and carried out functional studies of glycosylation, structure-guided mutagenesis, and patch-clamp recording. J.C.S. participated in the structure refinement, analysis and manuscript writing. Z.Z.W. supervised the project, conducted biochemical and pharmacological assays, electrophysiological recordings, and data analyses, and wrote part of the manuscript. L.C. supervised the project, collected X-ray diffraction data, solved and interpreted the structure, and wrote the manuscript together with C.D.D.

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Correspondence to Zuo-Zhong Wang or Lin Chen.

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Dellisanti, C., Yao, Y., Stroud, J. et al. Crystal structure of the extracellular domain of nAChR α1 bound to α-bungarotoxin at 1.94 Å resolution. Nat Neurosci 10, 953–962 (2007). https://doi.org/10.1038/nn1942

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