Structural heterogeneity of cellular K5/K14 filaments as revealed by cryo-electron microscopy

  1. Miriam S Weber
  2. Matthias Eibauer
  3. Suganya Sivagurunathan
  4. Thomas M Magin
  5. Robert D Goldman
  6. Ohad Medalia  Is a corresponding author
  1. University of Zürich, Switzerland
  2. Northwestern University Feinberg School of Medicine, United States
  3. University of Leipzig, Germany

Abstract

Keratin intermediate filaments are an essential and major component of the cytoskeleton in epithelial cells. They form a stable yet dynamic filamentous network extending from the nucleus to the cell periphery, which provides resistance to mechanical stresses. Mutations in keratin genes are related to a variety of epithelial tissue diseases. Despite their importance, the molecular structure of keratin filaments remains largely unknown. In this study, we analyzed the structure of keratin 5/keratin 14 filaments within ghost mouse keratinocytes by cryo-electron microscopy and cryo-electron tomography. By averaging a large number of keratin segments, we have gained insights into the helical architecture of the filaments. Two-dimensional classification revealed profound variations in the diameter of keratin filaments and their subunit organization. Computational reconstitution of filaments of substantial length uncovered a high degree of internal heterogeneity along single filaments, which can contain regions of helical symmetry, regions with less symmetry and regions with significant diameter fluctuations. Cross section views of filaments revealed that keratins form hollow cylinders consisting of multiple protofilaments, with an electron dense core located in the center of the filament. These findings shed light on the complex and remarkable heterogenic architecture of keratin filaments, suggesting that they are highly flexible, dynamic cytoskeletal structures.

Data availability

Representative cryo-ET data have been deposited in the Electron Microscopy Data Bank under accession codes EMD-12958 and EMD-12959. In addition, data was uploaded to https://doi.org/10.5061/dryad.gqnk98sn4.

The following data sets were generated

Article and author information

Author details

  1. Miriam S Weber

    University of Zürich, Zurich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  2. Matthias Eibauer

    University of Zürich, Zurich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  3. Suganya Sivagurunathan

    Northwestern University Feinberg School of Medicine, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Thomas M Magin

    Institute of Biology and Translational Center for Regenerative Medicine, University of Leipzig, Leipzig, Germany
    Competing interests
    The authors declare that no competing interests exist.
  5. Robert D Goldman

    Northwestern University Feinberg School of Medicine, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Ohad Medalia

    University of Zürich, Zurich, Switzerland
    For correspondence
    omedalia@bioc.uzh.ch
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-0994-2937

Funding

Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (31003A_179418)

  • Ohad Medalia

NIH Office of the Director (5PO1 GM096971)

  • Robert D Goldman

NIH Office of the Director (RO1GM140108)

  • Robert D Goldman

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

Copyright

© 2021, Weber 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. Miriam S Weber
  2. Matthias Eibauer
  3. Suganya Sivagurunathan
  4. Thomas M Magin
  5. Robert D Goldman
  6. Ohad Medalia
(2021)
Structural heterogeneity of cellular K5/K14 filaments as revealed by cryo-electron microscopy
eLife 10:e70307.
https://doi.org/10.7554/eLife.70307

Share this article

https://doi.org/10.7554/eLife.70307

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