Kinetic mechanism of coupled binding in sodium-aspartate symporter GltPh

  1. SeCheol Oh
  2. Olga Boudker  Is a corresponding author
  1. Weill Cornell Medicine, United States

Abstract

Many secondary active membrane transporters pump substrates against concentration gradients by coupling their uptake to symport of sodium ions. Symport requires the substrate and ions to be always transported together. Cooperative binding of the solutes is a key mechanism contributing to coupled transport in the sodium and aspartate symporter from Pyrococcus horikoshii GltPh. Here, we describe the kinetic mechanism of coupled binding for GltPh in the inward facing state. The first of the three coupled sodium ions, binds weakly and slowly, enabling the protein to accept the rest of the ions and the substrate. The last ion binds tightly, but is in rapid equilibrium with solution. Its release is required for the complex disassembly. Thus, the first ion serves to 'open the door' for the substrate, the last ion 'locks the door' once the substrate is in, and one ion contributes to both events.

Data availability

Diffraction data have been deposited in PDB under the accession code 6CTF

The following data sets were generated

Article and author information

Author details

  1. SeCheol Oh

    Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States
    Competing interests
    No competing interests declared.
  2. Olga Boudker

    Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States
    For correspondence
    olb2003@med.cornell.edu
    Competing interests
    Olga Boudker, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6965-0851

Funding

Howard Hughes Medical Institute

  • Olga Boudker

National Institute of Neurological Disorders and Stroke (R01NS064357)

  • Olga Boudker

National Institute of Neurological Disorders and Stroke (R37NS085318)

  • Olga Boudker

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

Reviewing Editor

  1. José D Faraldo-Gómez, National Heart, Lung and Blood Institute, National Institutes of Health, United States

Version history

  1. Received: April 5, 2018
  2. Accepted: September 25, 2018
  3. Accepted Manuscript published: September 26, 2018 (version 1)
  4. Version of Record published: October 8, 2018 (version 2)

Copyright

© 2018, Oh & Boudker

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.

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  1. SeCheol Oh
  2. Olga Boudker
(2018)
Kinetic mechanism of coupled binding in sodium-aspartate symporter GltPh
eLife 7:e37291.
https://doi.org/10.7554/eLife.37291

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https://doi.org/10.7554/eLife.37291

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