Structural heterogeneity of cellular K5/K14 filaments as revealed by cryo-electron microscopy
- University of Zürich, Switzerland
- Northwestern University Feinberg School of Medicine, United States
- 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.
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Structural heterogeneity of cellular K5/K14 filaments as revealed by cryo-electron microscopyhttps://creativecommons.org/publicdomain/zero/1.0/.
Article and author information
Author details
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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Structural heterogeneity of cellular K5/K14 filaments as revealed by cryo-electron microscopy
eLife 10:e70307.
https://doi.org/10.7554/eLife.70307
