Structural basis of αE-catenin-F-actin catch bond behavior

  1. Xiao-Ping Xu
  2. Sabine Pokutta
  3. Megan Torres
  4. Mark F Swift
  5. Dorit Hanein  Is a corresponding author
  6. Niels Volkmann  Is a corresponding author
  7. William I Weis  Is a corresponding author
  1. Scintillon Institute, United States
  2. Stanford University, United States
  3. Stanford University School of Medicine, United States

Abstract

Cell-cell and cell-matrix junctions transmit mechanical forces during tissue morphogenesis and homeostasis. α-Catenin links cell-cell adhesion complexes to the actin cytoskeleton, and mechanical load strengthens its binding to F-actin in a direction-sensitive manner. Specifically, optical trap experiments revealed that force promotes a transition between weak and strong actin-bound states. Here, we describe the cryo-electron microscopy structure of the F-actin-bound αE-catenin actin-binding domain, which in solution forms a 5-helix bundle. In the actin-bound structure, the first helix of the bundle dissociates and the remaining four helices and connecting loops rearrange to form the interface with actin. Deletion of the first helix produces strong actin binding in the absence of force, suggesting that the actin-bound structure corresponds to the strong state. Our analysis explains how mechanical force applied to αE-catenin or its homolog vinculin favors the strongly bound state, and the dependence of catch bond strength on the direction of applied force.

Data availability

The coordinates and cryo-EM map of the aE-catenin-F-actin complex have been deposited in the Protein Data Bank, identifiers 6WVT and EMD-21925, respectively

Article and author information

Author details

  1. Xiao-Ping Xu

    Scintillon Institute, Scintillon Institute, San Diego, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Sabine Pokutta

    Department of Structural Biology, Stanford University, Stanford, CA, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Megan Torres

    Structural Biology and Molecular & Cellular Physiology, Stanford University, Stanford, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Mark F Swift

    Scintillon Institute, Scintillon Institute, San Diego, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Dorit Hanein

    Scintillon Institute, Scintillon Institute, San Diego, United States
    For correspondence
    dorit@scintillon.org
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6072-4946
  6. Niels Volkmann

    Scintillon Institute, Scintillon Institute, San Diego, United States
    For correspondence
    niels@sbpdiscovery.org
    Competing interests
    The authors declare that no competing interests exist.
  7. William I Weis

    Departments of Structural Biology and of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, United States
    For correspondence
    weis@stanford.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5583-6150

Funding

National Institutes of Health (GM118326)

  • Dorit Hanein
  • Niels Volkmann
  • William I Weis

National Institutes of Health (GM131747)

  • William I Weis

National Institutes of Health (S10-OD012372)

  • Dorit Hanein

National Institutes of Health (S10-OD026926)

  • Dorit Hanein

Pew Charitable Trusts (864K625)

  • Dorit Hanein

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

Reviewing Editor

  1. Christopher P Hill, University of Utah School of Medicine, United States

Version history

  1. Received: July 9, 2020
  2. Accepted: September 9, 2020
  3. Accepted Manuscript published: September 11, 2020 (version 1)
  4. Version of Record published: October 26, 2020 (version 2)

Copyright

© 2020, Xu 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

  • 2,455
    views
  • 382
    downloads
  • 48
    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. Xiao-Ping Xu
  2. Sabine Pokutta
  3. Megan Torres
  4. Mark F Swift
  5. Dorit Hanein
  6. Niels Volkmann
  7. William I Weis
(2020)
Structural basis of αE-catenin-F-actin catch bond behavior
eLife 9:e60878.
https://doi.org/10.7554/eLife.60878

Share this article

https://doi.org/10.7554/eLife.60878

Further reading

    1. Cell Biology
    2. Structural Biology and Molecular Biophysics
    Lin Mei, Santiago Espinosa de los Reyes ... Gregory M Alushin
    Research Article Updated

    The actin cytoskeleton mediates mechanical coupling between cells and their tissue microenvironments. The architecture and composition of actin networks are modulated by force; however, it is unclear how interactions between actin filaments (F-actin) and associated proteins are mechanically regulated. Here we employ both optical trapping and biochemical reconstitution with myosin motor proteins to show single piconewton forces applied solely to F-actin enhance binding by the human version of the essential cell-cell adhesion protein αE-catenin but not its homolog vinculin. Cryo-electron microscopy structures of both proteins bound to F-actin reveal unique rearrangements that facilitate their flexible C-termini refolding to engage distinct interfaces. Truncating α-catenin’s C-terminus eliminates force-activated F-actin binding, and addition of this motif to vinculin confers force-activated binding, demonstrating that α-catenin’s C-terminus is a modular detector of F-actin tension. Our studies establish that piconewton force on F-actin can enhance partner binding, which we propose mechanically regulates cellular adhesion through α-catenin.

    1. Structural Biology and Molecular Biophysics
    Hitendra Negi, Aravind Ravichandran ... Ranabir Das
    Research Article

    The proteasome controls levels of most cellular proteins, and its activity is regulated under stress, quiescence, and inflammation. However, factors determining the proteasomal degradation rate remain poorly understood. Proteasome substrates are conjugated with small proteins (tags) like ubiquitin and Fat10 to target them to the proteasome. It is unclear if the structural plasticity of proteasome-targeting tags can influence substrate degradation. Fat10 is upregulated during inflammation, and its substrates undergo rapid proteasomal degradation. We report that the degradation rate of Fat10 substrates critically depends on the structural plasticity of Fat10. While the ubiquitin tag is recycled at the proteasome, Fat10 is degraded with the substrate. Our results suggest significantly lower thermodynamic stability and faster mechanical unfolding in Fat10 compared to ubiquitin. Long-range salt bridges are absent in the Fat10 structure, creating a plastic protein with partially unstructured regions suitable for proteasome engagement. Fat10 plasticity destabilizes substrates significantly and creates partially unstructured regions in the substrate to enhance degradation. NMR-relaxation-derived order parameters and temperature dependence of chemical shifts identify the Fat10-induced partially unstructured regions in the substrate, which correlated excellently to Fat10-substrate contacts, suggesting that the tag-substrate collision destabilizes the substrate. These results highlight a strong dependence of proteasomal degradation on the structural plasticity and thermodynamic properties of the proteasome-targeting tags.