1. Structural Biology and Molecular Biophysics
  2. Computational and Systems Biology
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Substrate transport and anion permeation proceed through distinct pathways in glutamate transporters

  1. Mary Hongying Cheng
  2. Delany Torres-Salazar
  3. Aneysis D Gonzalez-Suarez
  4. Susan G Amara
  5. Ivet Bahar  Is a corresponding author
  1. School of Medicine, University of Pittsburgh, United States
  2. National Institutes of Health, United States
Research Article
  • Cited 15
  • Views 1,370
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Cite this article as: eLife 2017;6:e25850 doi: 10.7554/eLife.25850

Abstract

Advances in structure-function analyses and computational biology have enabled a deeper understanding of how excitatory amino acid transporters (EAATs) mediate chloride permeation and substrate transport. However, the mechanism of structural coupling between these functions remains to be established. Using a combination of molecular modeling, substituted cysteine accessibility, electrophysiology and glutamate uptake assays, we identified a chloride-channeling conformer, iChS, transiently accessible as EAAT1 reconfigures from substrate/ion-loaded into a substrate-releasing conformer. Opening of the anion permeation path in this iChS is controlled by the elevator-like movement of the substrate-binding core, along with its wall that simultaneously lines the anion permeation path (global); and repacking of a cluster of hydrophobic residues near the extracellular vestibule (local). Moreover, our results demonstrate that stabilization of iChS by chemical modifications favors anion channeling at the expense of substrate transport, suggesting a mutually exclusive regulation mediated by the movement of the flexible wall lining the two regions.

Article and author information

Author details

  1. Mary Hongying Cheng

    Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Delany Torres-Salazar

    Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Aneysis D Gonzalez-Suarez

    Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Susan G Amara

    Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Ivet Bahar

    Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
    For correspondence
    bahar@pitt.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9959-4176

Funding

NIH (P41GM103712)

  • Ivet Bahar

NIH (P30DA035778)

  • Ivet Bahar

NIH (5R01GM099738)

  • Ivet Bahar

NIH (MH002946)

  • Susan G Amara

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

Reviewing Editor

  1. Yibing Shan, DE Shaw Research, United States

Publication history

  1. Received: February 8, 2017
  2. Accepted: May 10, 2017
  3. Accepted Manuscript published: June 1, 2017 (version 1)
  4. Version of Record published: June 15, 2017 (version 2)

Copyright

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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