1. Structural Biology and Molecular Biophysics
Download icon

A sulfur-aromatic gate latch is essential for opening of the Orai1 channel pore

  1. Priscilla S-W Yeung
  2. Christopher E Ing
  3. Megumi Yamashita
  4. Régis Pomès
  5. Murali Prakriya  Is a corresponding author
  1. Northwestern University Feinberg School of Medicine, United States
  2. Hospital for Sick Children, Canada
  3. The Hospital for Sick Children, Canada
Research Article
  • Cited 0
  • Views 312
  • Annotations
Cite this article as: eLife 2020;9:e60751 doi: 10.7554/eLife.60751

Abstract

Sulfur-aromatic interactions occur in the majority of protein structures, yet little is known about their functional roles in ion channels. Here, we describe a novel molecular motif, the M101 gate latch, which is essential for gating of human Orai1 channels via its sulfur-aromatic interactions with the F99 hydrophobic gate. Molecular dynamics simulations of different Orai variants reveal that the gate latch is engaged in open but not in closed channels. In experimental studies, we use metal ion bridges to show that promoting an M101-F99 bond directly activates Orai1, whereas disrupting this interaction triggers channel closure. Mutational analysis demonstrates that methionine at this position has a unique length, flexibility, and chemistry to act as an effective latch for the phenylalanine gate. Because sulfur-aromatic interactions provide additional stabilization compared to purely hydrophobic interactions, we postulate that the six M101-F99 pairs in the hexameric channel represent a substantial energetic contribution to Orai1 activation.

Article and author information

Author details

  1. Priscilla S-W Yeung

    Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Christopher E Ing

    Molecular Structure and Function, Hospital for Sick Children, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6947-5731
  3. Megumi Yamashita

    Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Régis Pomès

    Molecular Structure and Function, The Hospital for Sick Children, Toronto, Canada
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3068-9833
  5. Murali Prakriya

    Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
    For correspondence
    m-prakriya@northwestern.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-0781-4480

Funding

National Institutes of Health (NS057499)

  • Murali Prakriya

National Institutes of Health (F31NS101830)

  • Priscilla S-W Yeung

Canadian Institutes of Health Research (MOP130461)

  • Régis Pomès

National Institutes of Health (GM114210)

  • Murali Prakriya

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

Reviewing Editor

  1. Richard S Lewis, Stanford University School of Medicine, United States

Publication history

  1. Received: July 6, 2020
  2. Accepted: October 27, 2020
  3. Accepted Manuscript published: October 30, 2020 (version 1)

Copyright

? 2020, Yeung 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

  • 312
    Page views
  • 94
    Downloads
  • 0
    Citations

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

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)

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

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

Further reading

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics
    Sandip Basak et al.
    Research Article Updated

    Serotonin receptors (5-HT3AR) play a crucial role in regulating gut movement, and are the principal target of setrons, a class of high-affinity competitive antagonists, used in the management of nausea and vomiting associated with radiation and chemotherapies. Structural insights into setron-binding poses and their inhibitory mechanisms are just beginning to emerge. Here, we present high-resolution cryo-EM structures of full-length 5-HT3AR in complex with palonosetron, ondansetron, and alosetron. Molecular dynamic simulations of these structures embedded in a fully-hydrated lipid environment assessed the stability of ligand-binding poses and drug-target interactions over time. Together with simulation results of apo- and serotonin-bound 5-HT3AR, the study reveals a distinct interaction fingerprint between the various setrons and binding-pocket residues that may underlie their diverse affinities. In addition, varying degrees of conformational change in the setron-5-HT3AR structures, throughout the channel and particularly along the channel activation pathway, suggests a novel mechanism of competitive inhibition.

    1. Immunology and Inflammation
    2. Structural Biology and Molecular Biophysics
    Christopher T Boughter et al.
    Research Article

    Antibodies are critical components of adaptive immunity, binding with high affinity to pathogenic epitopes. Antibodies undergo rigorous selection to achieve this high affinity, yet some maintain an additional basal level of low affinity, broad reactivity to diverse epitopes, a phenomenon termed 'polyreactivity'. While polyreactivity has been observed in antibodies isolated from various immunological niches, the biophysical properties that allow for promiscuity in a protein selected for high affinity binding to a single target remain unclear. Using a database of over 1,000 polyreactive and non-polyreactive antibody sequences, we created a bioinformatic pipeline to isolate key determinants of polyreactivity. These determinants, which include an increase in inter-loop crosstalk and a propensity for a neutral binding surface, are sufficient to generate a classifier able to identify polyreactive antibodies with over 75% accuracy. The framework from which this classifier was built is generalizable, and represents a powerful, automated pipeline for future immune repertoire analysis.