1. Biochemistry and Chemical Biology
  2. Structural Biology and Molecular Biophysics

Structures reveal gatekeeping of the mitochondrial Ca2+ uniporter by MICU1-MICU2

  1. Chongyuan Wang
  2. Agata Jacewicz
  3. Bryce D Delgado
  4. Rozbeh Baradaran
  5. Stephen Barstow Long  Is a corresponding author
  1. Memorial Sloan Kettering Cancer Center, United States
https://doi.org/10.7554/eLife.59991
Share this article
Cite this article
  1. Chongyuan Wang
  2. Agata Jacewicz
  3. Bryce D Delgado
  4. Rozbeh Baradaran
  5. Stephen Barstow Long
(2020)
Structures reveal gatekeeping of the mitochondrial Ca2+ uniporter by MICU1-MICU2
eLife 9:e59991.
https://doi.org/10.7554/eLife.59991
  2. Download BibTeX
  3. Download .RIS

Abstract

The mitochondrial calcium uniporter is a Ca2+-gated ion channel complex that controls mitochondrial Ca2+ entry and regulates cell metabolism. MCU and EMRE form the channel while Ca2+-dependent regulation is conferred by MICU1 and MICU2 through an enigmatic process. We present a cryo-EM structure of an MCU-EMRE-MICU1-MICU2 holocomplex comprising MCU and EMRE subunits from the beetle Tribolium castaneum in complex with a human MICU1-MICU2 heterodimer at 3.3 Å resolution. With analogy to how neuronal channels are blocked by protein toxins, a uniporter interaction domain on MICU1 binds to a channel receptor site comprising MCU and EMRE subunits to inhibit ion flow under resting Ca2+ conditions. A Ca2+-bound structure of MICU1-MICU2 at 3.1 Å resolution indicates how Ca2+-dependent changes enable dynamic response to cytosolic Ca2+ signals.

Data availability

The atomic coordinates and EM maps have been deposited in the Protein Data Bank (www.rcsb.org) and the EMDB (www.ebi.ac.uk/pdbe/emdb/): PDB ID 6XQN, EMDB ID EMD-22290 (holocomplex in low Ca2+); PDB ID 6XQO, EMDB ID EMD-22291 (Ca2+-bound MICU1-MICU2 heterodimer).

The following data sets were generated

Article and author information

Author details

  1. Chongyuan Wang

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Agata Jacewicz

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Bryce D Delgado

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  4. Rozbeh Baradaran

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Stephen Barstow Long

    Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
    For correspondence
    longs@mskcc.org
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8144-1398

Funding

National Institute of General Medical Sciences (R35GM131921)

  • Stephen Barstow Long

National Cancer Institute (P30CA008748)

  • Stephen Barstow Long

National Institute of General Medical Sciences (5T32GM008539)

  • Bryce D Delgado

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

Copyright

© 2020, Wang 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.

Metrics

  • 3,144
    views
  • 547
    downloads
  • 45
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Chongyuan Wang
  2. Agata Jacewicz
  3. Bryce D Delgado
  4. Rozbeh Baradaran
  5. Stephen Barstow Long
(2020)
Structures reveal gatekeeping of the mitochondrial Ca2+ uniporter by MICU1-MICU2
eLife 9:e59991.
https://doi.org/10.7554/eLife.59991

Share this article

https://doi.org/10.7554/eLife.59991

Categories and tags

Research organism

Further reading

    1. Biochemistry and Chemical Biology
    2. Cell Biology

    Two-way Dispatched function in Sonic hedgehog shedding and transfer to high-density lipoproteins

    Kristina Ehring, Sophia Friederike Ehlers ... Kay Grobe
    Research Article

    The Sonic hedgehog (Shh) signaling pathway controls embryonic development and tissue homeostasis after birth. This requires regulated solubilization of dual-lipidated, firmly plasma membrane-associated Shh precursors from producing cells. Although it is firmly established that the resistance-nodulation-division transporter Dispatched (Disp) drives this process, it is less clear how lipidated Shh solubilization from the plasma membrane is achieved. We have previously shown that Disp promotes proteolytic solubilization of Shh from its lipidated terminal peptide anchors. This process, termed shedding, converts tightly membrane-associated hydrophobic Shh precursors into delipidated soluble proteins. We show here that Disp-mediated Shh shedding is modulated by a serum factor that we identify as high-density lipoprotein (HDL). In addition to serving as a soluble sink for free membrane cholesterol, HDLs also accept the cholesterol-modified Shh peptide from Disp. The cholesteroylated Shh peptide is necessary and sufficient for Disp-mediated transfer because artificially cholesteroylated mCherry associates with HDL in a Disp-dependent manner, whereas an N-palmitoylated Shh variant lacking C-cholesterol does not. Disp-mediated Shh transfer to HDL is completed by proteolytic processing of the palmitoylated N-terminal membrane anchor. In contrast to dual-processed soluble Shh with moderate bioactivity, HDL-associated N-processed Shh is highly bioactive. We propose that the purpose of generating different soluble forms of Shh from the dual-lipidated precursor is to tune cellular responses in a tissue-type and time-specific manner.

    1. Biochemistry and Chemical Biology
    2. Cell Biology

    Point of View: Teaching troubleshooting skills to graduate students

    Gina Partipilo, Yang Gao ... Benjamin K Keitz
    Feature Article

    Troubleshooting is an important part of experimental research, but graduate students rarely receive formal training in this skill. In this article, we describe an initiative called Pipettes and Problem Solving that we developed to teach troubleshooting skills to graduate students at the University of Texas at Austin. An experienced researcher presents details of a hypothetical experiment that has produced unexpected results, and students have to propose new experiments that will help identify the source of the problem. We also provide slides and other resources that can be used to facilitate problem solving and teach troubleshooting skills at other institutions.

    1. Biochemistry and Chemical Biology
    2. Plant Biology

    Structure and evolution of alanine/serine decarboxylases and the engineering of theanine production

    Hao Wang, Biying Zhu ... Zhaoliang Zhang
    Research Article

    Ethylamine (EA), the precursor of theanine biosynthesis, is synthesized from alanine decarboxylation by alanine decarboxylase (AlaDC) in tea plants. AlaDC evolves from serine decarboxylase (SerDC) through neofunctionalization and has lower catalytic activity. However, lacking structure information hinders the understanding of the evolution of substrate specificity and catalytic activity. In this study, we solved the X-ray crystal structures of AlaDC from Camellia sinensis (CsAlaDC) and SerDC from Arabidopsis thaliana (AtSerDC). Tyr341 of AtSerDC or the corresponding Tyr336 of CsAlaDC is essential for their enzymatic activity. Tyr111 of AtSerDC and the corresponding Phe106 of CsAlaDC determine their substrate specificity. Both CsAlaDC and AtSerDC have a distinctive zinc finger and have not been identified in any other Group II PLP-dependent amino acid decarboxylases. Based on the structural comparisons, we conducted a mutation screen of CsAlaDC. The results indicated that the mutation of L110F or P114A in the CsAlaDC dimerization interface significantly improved the catalytic activity by 110% and 59%, respectively. Combining a double mutant of CsAlaDCL110F/P114A with theanine synthetase increased theanine production 672% in an in vitro system. This study provides the structural basis for the substrate selectivity and catalytic activity of CsAlaDC and AtSerDC and provides a route to more efficient biosynthesis of theanine.