Microtubules soften due to cross-sectional flattening

  1. Edvin Memet
  2. Feodor Hilitsk
  3. Margaret A Morris
  4. Walter J Schwenger
  5. Zvonimir Dogic
  6. L Mahadevan  Is a corresponding author
  1. Harvard University, United States
  2. Brandeis University, United States
  3. University of California, Santa Barbara, United States

Abstract

We use optical trapping to continuously bend an isolated microtubule while simultaneously measuring the applied force and the resulting filament strain, thus allowing us to determine its elastic properties over a wide range of applied strains. We find that, while in the low-strain regime, microtubules may be quantitatively described in terms of the classical Euler-Bernoulli elastic filament, above a critical strain they deviate from this simple elastic model, showing a softening response with increasing deformations. A three-dimensional thin-shell model, in which the increased mechanical compliance is caused by flattening and eventual buckling of the filament cross-section, captures this softening effect in the high strain regime and yields quantitative values of the effective mechanical properties of microtubules. Our results demonstrate that properties of microtubules are highly dependent on the magnitude of the applied strain and offer a new interpretation for the large variety in microtubule mechanical data measured by different methods.

Data availability

Source data has been provided for Figure 6 along with source code files. Source code files have been provided for Figure 2 along with instructions for generating the data.

The following previously published data sets were used

Article and author information

Author details

  1. Edvin Memet

    Department of Physics, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9414-597X
  2. Feodor Hilitsk

    Department of Physics, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5629-1407
  3. Margaret A Morris

    Department of Physics, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Walter J Schwenger

    Department of Physics, Brandeis University, Waltham, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Zvonimir Dogic

    Department of Physics, University of California, Santa Barbara, Santa Barbara, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. L Mahadevan

    Department of Physics, Harvard University, Cambridge, United States
    For correspondence
    lm@seas.harvard.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5114-0519

Funding

U.S. Department of Energy (DE-SC0010432TDD)

  • Feodor Hilitsk
  • Zvonimir Dogic

National Science Foundation (NSF-MCB-1329623)

  • Zvonimir Dogic

National Science Foundation (NSF- -CMMI-1068566)

  • Zvonimir Dogic

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

Reviewing Editor

  1. Manuel Thery, CEA, France

Publication history

  1. Received: February 6, 2018
  2. Accepted: June 1, 2018
  3. Accepted Manuscript published: June 1, 2018 (version 1)
  4. Version of Record published: July 12, 2018 (version 2)
  5. Version of Record updated: February 28, 2019 (version 3)

Copyright

© 2018, Memet 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. Edvin Memet
  2. Feodor Hilitsk
  3. Margaret A Morris
  4. Walter J Schwenger
  5. Zvonimir Dogic
  6. L Mahadevan
(2018)
Microtubules soften due to cross-sectional flattening
eLife 7:e34695.
https://doi.org/10.7554/eLife.34695

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