1. Cell Biology
  2. Structural Biology and Molecular Biophysics

Molecular mechanism for direct actin force-sensing by α-catenin

  1. Lin Mei
  2. Santiago Espinosa de los Reyes
  3. Matthew J Reynolds
  4. Rachel Leicher
  5. Shixin Liu
  6. Gregory M Alushin  Is a corresponding author
  1. The Rockefeller University, United States
https://doi.org/10.7554/eLife.62514
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  1. Lin Mei
  2. Santiago Espinosa de los Reyes
  3. Matthew J Reynolds
  4. Rachel Leicher
  5. Shixin Liu
  6. Gregory M Alushin
(2020)
Molecular mechanism for direct actin force-sensing by α-catenin
eLife 9:e62514.
https://doi.org/10.7554/eLife.62514
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Abstract

The actin cytoskeleton mediates mechanical coupling between cells and their tissue microenvironments. The architecture and composition of actin networks are modulated by force, but 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 a-catenin.

Data availability

The atomic coordinates for the metavinculin ABD-F-actin complex and α-catenin ABD-F-actin complex have been deposited in the Protein Data Bank (PDB) with accession codes 6UPW and 6UPV, and the corresponding cryo-EM density maps in the Electron Microscopy Data Bank (EMDB) with accession codes EMD-20844 and EMD-20843.The code for analyzing TIRF movies is freely available as an ImageJ plugin with a graphical user interface at https://github.com/alushinlab/ActinEnrichment. All other data are available in the manuscript or supplementary materials.

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Author details

  1. Lin Mei

    Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5056-4547

  2. Santiago Espinosa de los Reyes

    Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4510-8296

  3. Matthew J Reynolds

    Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2501-9280

  4. Rachel Leicher

    Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Shixin Liu

    Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4238-7066

  6. Gregory M Alushin

    Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, United States
    For correspondence
    galushin@rockefeller.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7250-4484

Funding

Irma T. Hirschl Trust (Research Award)

  • Gregory M Alushin

Pew Charitable Trusts (Pew Scholar Award)

  • Gregory M Alushin

National Institutes of Health (5DP5OD017885)

  • Gregory M Alushin

National Institutes of Health (1DP2HG010510)

  • Shixin Liu

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

Copyright

© 2020, Mei 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. Lin Mei
  2. Santiago Espinosa de los Reyes
  3. Matthew J Reynolds
  4. Rachel Leicher
  5. Shixin Liu
  6. Gregory M Alushin
(2020)
Molecular mechanism for direct actin force-sensing by α-catenin
eLife 9:e62514.
https://doi.org/10.7554/eLife.62514

Share this article

https://doi.org/10.7554/eLife.62514

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    1. Structural Biology and Molecular Biophysics

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

    Xiao-Ping Xu, Sabine Pokutta ... William I Weis
    Research Article Updated

    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 five-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.