Measurements and simulations of microtubule growth imply strong longitudinal interactions and reveal a role for GDP on the elongating end

  1. Joseph M Cleary
  2. Tae Kim
  3. Annan SI Cook
  4. Lauren A McCormick
  5. William O Hancock  Is a corresponding author
  6. Luke M Rice  Is a corresponding author
  1. Pennsylvania State University, United States
  2. The University of Texas Southwestern Medical Center, United States

Abstract

Microtubule polymerization dynamics result from the biochemical interactions of αβ-tubulin with the polymer end, but a quantitative understanding has been challenging to establish. We used interference reflection microscopy to make improved measurements of microtubule growth rates and growth fluctuations in the presence and absence of GTP hydrolysis. In the absence of GTP hydrolysis, microtubules grew steadily with very low fluctuations. These data were best described by a computational model implementing slow assembly kinetics, such that the rate of microtubule elongation is primarily limited by the rate of αβ-tubulin associations. With GTPase present, microtubules displayed substantially larger growth fluctuations than expected based on the no GTPase measurements. Our modeling showed that these larger fluctuations occurred because exposure of GDP-tubulin on the microtubule end transiently 'poisoned' growth, yielding a wider range of growth rates compared to GTP only conditions. Our experiments and modeling point to slow association kinetics (strong longitudinal interactions), such that drugs and regulatory proteins that alter microtubule dynamics could do so by modulating either the association or dissociation rate of tubulin from the microtubule tip. By causing slower growth, exposure of GDP tubulin at the growing microtubule end may be an important early event determining catastrophe.

Data availability

Numerical data used to generate most of the figures have been provided as Source Data.

Article and author information

Author details

  1. Joseph M Cleary

    Department of Biomedical Engineering, Pennsylvania State University, University Park, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Tae Kim

    Departments of Biophysics and Biochemistry, The University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Annan SI Cook

    Department of Biomedical Engineering, Pennsylvania State University, University Park, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Lauren A McCormick

    Departments of Biophysics and Biochemistry, The University of Texas Southwestern Medical Center, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9164-0932
  5. William O Hancock

    Department of Biomedical Engineering, Pennsylvania State University, University Park, United States
    For correspondence
    woh1@psu.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5547-8755
  6. Luke M Rice

    Departments of Biophysics and Biochemistry, The University of Texas Southwestern Medical Center, Dallas, United States
    For correspondence
    Luke.Rice@UTSouthwestern.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6551-3307

Funding

National Science Foundation (MCB-1615938)

  • Tae Kim
  • Lauren A McCormick
  • Luke M Rice

National Institutes of Health (R01-GM135565)

  • Lauren A McCormick
  • Luke M Rice

National Institutes of Health (R35-GM139568)

  • Joseph M Cleary
  • William O Hancock

National Institutes of Health (T32-GM108563)

  • Joseph M Cleary

National Institutes of Health (T32-GM008297)

  • Tae Kim

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

Reviewing Editor

  1. Thomas Surrey, Centre for Genomic Regulation (CRG), Spain

Version history

  1. Preprint posted: November 25, 2021 (view preprint)
  2. Received: November 29, 2021
  3. Accepted: April 13, 2022
  4. Accepted Manuscript published: April 14, 2022 (version 1)
  5. Version of Record published: May 3, 2022 (version 2)

Copyright

© 2022, Cleary 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. Joseph M Cleary
  2. Tae Kim
  3. Annan SI Cook
  4. Lauren A McCormick
  5. William O Hancock
  6. Luke M Rice
(2022)
Measurements and simulations of microtubule growth imply strong longitudinal interactions and reveal a role for GDP on the elongating end
eLife 11:e75931.
https://doi.org/10.7554/eLife.75931

Share this article

https://doi.org/10.7554/eLife.75931

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