Letter | Published:

Crystal structure of human glycine receptor-α3 bound to antagonist strychnine

Nature volume 526, pages 277280 (08 October 2015) | Download Citation

Abstract

Neurotransmitter-gated ion channels of the Cys-loop receptor family are essential mediators of fast neurotransmission throughout the nervous system and are implicated in many neurological disorders. Available X-ray structures of prokaryotic and eukaryotic Cys-loop receptors provide tremendous insights into the binding of agonists, the subsequent opening of the ion channel, and the mechanism of channel activation1,2,3,4,5,6,7,8. Yet the mechanism of inactivation by antagonists remains unknown. Here we present a 3.0 Å X-ray structure of the human glycine receptor-α3 homopentamer in complex with a high affinity, high-specificity antagonist, strychnine. Our structure allows us to explore in detail the molecular recognition of antagonists. Comparisons with previous structures reveal a mechanism for antagonist-induced inactivation of Cys-loop receptors, involving an expansion of the orthosteric binding site in the extracellular domain that is coupled to closure of the ion pore in the transmembrane domain.

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Accessions

Primary accessions

Protein Data Bank

Data deposits

Atomic coordinates and structure factors for the GlyRα3–strychnine complex have been deposited in the Protein Data Bank (PDB) under accession number 5CFB.

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Acknowledgements

We thank G. Ranieri and R. Walter at Shamrock Structures and the staff at beamlines 08-ID at the Canadian Light Source and 22-ID at the Advanced Photon Source for data collection. We are grateful to Z. Wang and J. Gingras for reviewing the manuscript.

Author information

Affiliations

  1. Department of Molecular Structure and Characterization, Amgen Inc., 360 Binney Street, Cambridge, Massachusetts 02142, USA

    • Xin Huang
    • , Klaus Michelsen
    •  & Paul L. Shaffer
  2. Department of Protein Technologies, Amgen Inc., 360 Binney Street, Cambridge, Massachusetts 02142, USA

    • Hao Chen
  3. Department of Neuroscience, Amgen Inc., 360 Binney Street, Cambridge, Massachusetts 02142, USA

    • Stephen Schneider

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Contributions

The authors have jointly contributed to project design, data analysis and manuscript preparation. P.L.S. performed initial construct design and purification experiments, structure solution, model building, and structural analysis; X.H. performed protein purifications, crystallization, model building, and structural analysis; H.C. performed cloning and expression experiments; K.M. performed SPR and ITC binding studies; S.S. performed functional testing; P.L.S. and X.H. wrote the manuscript with help from K.M., S.S., and H.C.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Xin Huang or Paul L. Shaffer.

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https://doi.org/10.1038/nature14972

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