1. Structural Biology and Molecular Biophysics

Structural and functional characterization of an otopetrin family proton channel

  1. Qingfeng Chen
  2. Weizhong Zeng
  3. Ji She
  4. Xiaochen Bai  Is a corresponding author
  5. Youxing Jiang  Is a corresponding author
  1. University of Texas Southwestern Medical Center, United States
https://doi.org/10.7554/eLife.46710
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  1. Qingfeng Chen
  2. Weizhong Zeng
  3. Ji She
  4. Xiaochen Bai
  5. Youxing Jiang
(2019)
Structural and functional characterization of an otopetrin family proton channel
eLife 8:e46710.
https://doi.org/10.7554/eLife.46710
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Abstract

The otopetrin (OTOP) proteins were recently characterized as proton channels. Here we present the cryo-EM structure of OTOP3 from Xenopus tropicalis (XtOTOP3) along with functional characterization of the channel. XtOTOP3 forms a homodimer with each subunit containing 12 transmembrane helices that can be divided into two structurally homologous halves; each half assembles as an α-helical barrel that could potentially serve as a proton conduction pore. Both pores open from the extracellular half before becoming occluded at a central constriction point consisting of three highly conserved residues - Gln232/585-Asp262/Asn623-Tyr322/666 (the constriction triads). Mutagenesis shows that the constriction triad from the second pore is less amenable to perturbation than that of the first pore, suggesting an unequal contribution between the two pores to proton transport. We also identified several key residues at the interface between the two pores that are functionally important, particularly Asp509, which confers intracellular pH-dependent desensitization to OTOP channels.

Data availability

The cryo-EM density map of the XtOTOP3 has been deposited in the Electron Microscopy Data Bank under accession numbers EMDB-0650. Atomic coordinate has been deposited in the Protein Data Bank under accession number 6O84.

The following data sets were generated

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Author details

  1. Qingfeng Chen

    Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Weizhong Zeng

    Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Ji She

    Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7006-6230

  4. Xiaochen Bai

    Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States
    For correspondence
    Xiaochen.Bai@UTSouthwestern.edu
    Competing interests
    The authors declare that no competing interests exist.

  5. Youxing Jiang

    Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
    For correspondence
    youxing.jiang@utsouthwestern.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1874-0504

Funding

National Institute of General Medical Sciences (GM079179)

  • Youxing Jiang

Howard Hughes Medical Institute

  • Youxing Jiang

Welch Foundation (I-1578)

  • Youxing Jiang

Cancer Prevention and Research Institute of Texas

  • Xiaochen Bai

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

Reviewing Editor

  1. Baron Chanda, University of Wisconsin-Madison, United States

Version history

  1. Received: March 9, 2019
  2. Accepted: April 11, 2019
  3. Accepted Manuscript published: April 11, 2019 (version 1)
  4. Version of Record published: April 25, 2019 (version 2)
  5. Version of Record updated: July 17, 2019 (version 3)

Copyright

© 2019, Chen 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.

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  1. Qingfeng Chen
  2. Weizhong Zeng
  3. Ji She
  4. Xiaochen Bai
  5. Youxing Jiang
(2019)
Structural and functional characterization of an otopetrin family proton channel
eLife 8:e46710.
https://doi.org/10.7554/eLife.46710

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