1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics
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The conserved aspartate ring of MCU mediates MICU1 binding and regulation in the mitochondrial calcium uniporter complex

  1. Charles B Phillips
  2. Chen-Wei Tsai
  3. Ming-Feng Tsai  Is a corresponding author
  1. Brandeis University, United States
  2. University of Colorado Anschutz Medical Campus, United States
Research Article
  • Cited 20
  • Views 1,739
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Cite this article as: eLife 2019;8:e41112 doi: 10.7554/eLife.41112

Abstract

The mitochondrial calcium uniporter is a Ca2+ channel that regulates intracellular Ca2+ signaling, oxidative phosphorylation, and apoptosis. It contains the pore-forming MCU protein, which possesses a DIME sequence thought to form a Ca2+ selectivity filter, and also regulatory EMRE, MICU1, and MICU2 subunits. To properly carry out physiological functions, the uniporter must stay closed in resting conditions, becoming open only when stimulated by intracellular Ca2+ signals. This Ca2+-dependent activation, known to be mediated by MICU subunits, is not well understood. Here, we demonstrate that the DIME-aspartate mediates a Ca2+-modulated electrostatic interaction with MICU1, forming an MICU1 contact interface with a nearby Ser residue at the cytoplasmic entrance of the MCU pore. A mutagenesis screen of MICU1 identifies two highly-conserved Arg residues that might contact the DIME-Asp. Perturbing MCU-MICU1 interactions elicits unregulated, constitutive Ca2+ flux into mitochondria. These results indicate that MICU1 confers Ca2+-dependent gating of the uniporter by blocking/unblocking MCU.

Data availability

All data generated or analyzed during this study are included in the manuscript and supporting files. Source data for calcium-45 flux experiments are available via Dryad.

The following data sets were generated

Article and author information

Author details

  1. Charles B Phillips

    Department of Biochemistry, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Chen-Wei Tsai

    Department of Biochemistry, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Ming-Feng Tsai

    Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, United States
    For correspondence
    ming-feng.tsai@ucdenver.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4277-1885

Funding

Howard Hughes Medical Institute

  • Ming-Feng Tsai

National Institute of General Medical Sciences (R01-GM129345)

  • Chen-Wei Tsai
  • Ming-Feng Tsai

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. The funders pay for the authors' salary and other research expenses.

Reviewing Editor

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

Publication history

  1. Received: August 14, 2018
  2. Accepted: January 7, 2019
  3. Accepted Manuscript published: January 14, 2019 (version 1)
  4. Accepted Manuscript updated: January 15, 2019 (version 2)
  5. Version of Record published: January 25, 2019 (version 3)

Copyright

© 2019, Phillips 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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