1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics

Molecular mechanisms of gating in the calcium-activated chloride channel bestrophin

  1. Alexandria N Miller
  2. George Vaisey
  3. Stephen Barstow Long  Is a corresponding author
  1. Memorial Sloan Kettering Cancer Center, United States
https://doi.org/10.7554/eLife.43231
Share this article
Cite this article
  1. Alexandria N Miller
  2. George Vaisey
  3. Stephen Barstow Long
(2019)
Molecular mechanisms of gating in the calcium-activated chloride channel bestrophin
eLife 8:e43231.
https://doi.org/10.7554/eLife.43231
  2. Download BibTeX
  3. Download .RIS

Abstract

Bestrophin (BEST1-4) ligand-gated chloride (Cl-) channels are activated by calcium (Ca2+). Mutation of BEST1 causes retinal disease. Partly because bestrophin channels have no sequence or structural similarity to other ion channels, the molecular mechanisms underlying gating are unknown. Here, we present a series of cryo-electron microscopy structures of chicken BEST1, determined at 3.1 Å resolution or better, that represent the channel's principal gating states. Unlike other channels, opening of the pore is due to the repositioning of tethered pore-lining helices within a surrounding protein shell that dramatically widens a neck of the pore through a concertina of amino acid rearrangements. The neck serves as both the activation and the inactivation gate. Ca2+ binding instigates opening of the neck through allosteric means whereas inactivation peptide binding induces closing. An aperture within the otherwise wide pore controls anion permeability. The studies define a new molecular paradigm for gating among ligand-gated ion channels.

Data availability

Atomic coordinates and cryo-EM density maps of have been deposited with the PDB and Electron Microscopy Data Bank with the accession numbers: 6N23 (BEST1405, inactivated; EMD-9321), 6N24 (BEST1345 W287F mutant, Ca2+-free; EMD-9322), 6N25 (BEST1345 W287F mutant, Ca2+-bound; EMD-9323), 6N26 ( BEST1345 Ca2+-free closed state; EMD-9324), 6N27 (BEST1345 Ca2+-bound closed state; EMD-9325), and 6N28 ( BEST1345 Ca2+-bound open state; EMD-9326).

The following data sets were generated

Article and author information

Author details

  1. Alexandria N Miller

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. George Vaisey

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Stephen Barstow Long

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    For correspondence
    longs@mskcc.org
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8144-1398

Funding

National Institutes of Health (R01-GM110396)

  • Stephen Barstow Long

National Cancer Institute (P30 CA008748)

  • Stephen Barstow Long

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Kenton Jon Swartz, National Institute of Neurological Disorders and Stroke, National Institutes of Health, United States

Publication history

  1. Received: October 30, 2018
  2. Accepted: January 2, 2019
  3. Accepted Manuscript published: January 10, 2019 (version 1)
  4. Version of Record published: January 22, 2019 (version 2)
  5. Version of Record updated: January 23, 2019 (version 3)

Copyright

© 2019, Miller et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 4,536
    Page views
  • 679
    Downloads
  • 25
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, Scopus, PubMed Central.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Alexandria N Miller
  2. George Vaisey
  3. Stephen Barstow Long
(2019)
Molecular mechanisms of gating in the calcium-activated chloride channel bestrophin
eLife 8:e43231.
https://doi.org/10.7554/eLife.43231

Categories and tags

Further reading

  1. Ion channels: A Collection of Articles

    Edited by Kenton J Swartz et al.
    Collection

    eLife has published papers on topics related to the molecular structure and functional mechanisms of a diverse array of ion channel proteins.

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics

    Timeline of changes in spike conformational dynamics in emergent SARS-CoV-2 variants reveal progressive stabilization of trimer stalk with altered NTD dynamics

    Sean M Braet, Theresa SC Buckley ... Ganesh S Anand
    Research Article Updated

    SARS-CoV-2 emergent variants are characterized by increased viral fitness and each shows multiple mutations predominantly localized to the spike (S) protein. Here, amide hydrogen/deuterium exchange mass spectrometry has been applied to track changes in S dynamics from multiple SARS-CoV-2 variants. Our results highlight large differences across variants at two loci with impacts on S dynamics and stability. A significant enhancement in stabilization first occurred with the emergence of D614G S followed by smaller, progressive stabilization in subsequent variants. Stabilization preceded altered dynamics in the N-terminal domain, wherein Omicron BA.1 S showed the largest magnitude increases relative to other preceding variants. Changes in stabilization and dynamics resulting from S mutations detail the evolutionary trajectory of S in emerging variants. These carry major implications for SARS-CoV-2 viral fitness and offer new insights into variant-specific therapeutic development.

    1. Biochemistry and Chemical Biology

    Reserpine maintains photoreceptor survival in retinal ciliopathy by resolving proteostasis imbalance and ciliogenesis defects

    Holly Y Chen, Manju Swaroop ... Anand Swaroop
    Research Article

    Ciliopathies manifest from sensory abnormalities to syndromic disorders with multi-organ pathologies, with retinal degeneration a highly penetrant phenotype. Photoreceptor cell death is a major cause of incurable blindness in retinal ciliopathies. To identify drug candidates to maintain photoreceptor survival, we performed an unbiased, high-throughput screening of over 6,000 bioactive small molecules using retinal organoids differentiated from induced pluripotent stem cells (iPSC) of rd16 mouse, which is a model of Leber congenital amaurosis (LCA) type 10 caused by mutations in the cilia-centrosomal gene CEP290. We identified five non-toxic positive hits, including the lead molecule reserpine, which maintained photoreceptor development and survival in rd16 organoids. Reserpine also improved photoreceptors in retinal organoids derived from induced pluripotent stem cells of LCA10 patients and in rd16 mouse retina in vivo. Reserpine-treated patient organoids revealed modulation of signaling pathways related to cell survival/death, metabolism, and proteostasis. Further investigation uncovered dysregulation of autophagy associated with compromised primary cilium biogenesis in patient organoids and rd16 mouse retina. Reserpine partially restored the balance between autophagy and the ubiquitin-proteasome system at least in part by increasing the cargo adaptor p62, resulting in improved primary cilium assembly. Our study identifies effective drug candidates in preclinical studies of CEP290 retinal ciliopathies through cross-species drug discovery using iPSC-derived organoids, highlights the impact of proteostasis in the pathogenesis of ciliopathies, and provides new insights for treatments of retinal neurodegeneration.