1. Structural Biology and Molecular Biophysics
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Structural mechanisms of phospholipid activation of the human TPC2 channel

  1. Ji She
  2. Weizhong Zeng
  3. Jiangtao Guo
  4. Qingfeng Chen
  5. Xiaochen Bai  Is a corresponding author
  6. Youxing Jiang  Is a corresponding author
  1. University of Texas Southwestern Medical Center, United States
  2. Zhejiang University School of Medicine, China
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Cite this article as: eLife 2019;8:e45222 doi: 10.7554/eLife.45222

Abstract

Mammalian two-pore channels (TPCs) regulate the physiological functions of the endolysosome. Here we present cryo-EM structures of human TPC2 (HsTPC2), a phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2)-activated, Na+ selective channel, in the ligand-bound and apo states. The apo structure captures the closed conformation, while the ligand-bound form features the channel in both open and closed conformations. Combined with functional analysis, these structures provide insights into the mechanism of PI(3,5)P2-regulated gating of TPC2, which is distinct from that of TPC1. Specifically, the endolysosome-specific PI(3,5)P2 binds at the first 6-TM and activates the channel - independently of the membrane potential - by inducing a structural change at the pore-lining inner helix (IS6), which forms a continuous helix in the open state but breaks into two segments at Gly317 in the closed state. Additionally, structural comparison to the voltage-dependent TPC1 structure allowed us to identify Ile551 as being responsible for the loss of voltage dependence in TPC2.

Article and author information

Author details

  1. 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
  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. Jiangtao Guo

    Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, China
    Competing interests
    The authors declare that no competing interests exist.
  4. Qingfeng Chen

    Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. 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.
  6. 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

Howard Hughes Medical Institute

  • Youxing Jiang

National Institute of General Medical Sciences (GM079179)

  • Youxing Jiang

Welch Foundation (I-1578)

  • Youxing Jiang

Cancer Prevention and Research Initiative 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

Publication history

  1. Received: January 16, 2019
  2. Accepted: March 7, 2019
  3. Accepted Manuscript published: March 12, 2019 (version 1)
  4. Version of Record published: March 19, 2019 (version 2)
  5. Version of Record updated: July 17, 2019 (version 3)

Copyright

© 2019, She 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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