1. Cell Biology
  2. Structural Biology and Molecular Biophysics

Structural basis of tubulin recruitment and assembly by microtubule polymerases with Tumor Overexpressed Gene (TOG) domain arrays

  1. Stanley Nithianantham
  2. Brian D Cook
  3. Madielene Beans
  4. Fei Guo
  5. Fred Chang
  6. Jawdat Al-Bassam  Is a corresponding author
  1. University of California, Davis, United States
  2. University of California, San Francisco, United States
https://doi.org/10.7554/eLife.38922
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Cite this article
  1. Stanley Nithianantham
  2. Brian D Cook
  3. Madielene Beans
  4. Fei Guo
  5. Fred Chang
  6. Jawdat Al-Bassam
(2018)
Structural basis of tubulin recruitment and assembly by microtubule polymerases with Tumor Overexpressed Gene (TOG) domain arrays
eLife 7:e38922.
https://doi.org/10.7554/eLife.38922
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Abstract

XMAP215/Stu2/Alp14 proteins accelerate microtubule plus-end polymerization by recruiting tubulins via arrays of Tumor Overexpressed Gene (TOG) domains, yet their mechanism remains unknown. Here, we describe the biochemical and structural basis for TOG arrays in recruiting and polymerizing tubulins. Alp14 binds four tubulins via dimeric TOG1-TOG2 subunits, in which each domain exhibits a distinct exchange rate for tubulin. X-ray structures revealed square-shaped assemblies composed of pseudo-dimeric TOG1-TOG2 subunits assembled head-to-tail, positioning four unpolymerized tubulins in a polarized wheel-like configuration. Crosslinking and electron microscopy show Alp14-tubulin forms square assemblies in solution, and inactivating their interfaces destabilize this organization without influencing tubulin binding. An X-ray structure determined using approach to modulate tubulin polymerization revealed an unfurled assembly, in which TOG1-TOG2 uniquely bind to two polymerized tubulins. Our findings suggest a new microtubule polymerase model in which TOG arrays recruit tubulins by forming square assemblies that then unfurl, facilitating their concerted polymerization into protofilaments.

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Author details

  1. Stanley Nithianantham

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Brian D Cook

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Madielene Beans

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    The authors declare that no competing interests exist.

  4. Fei Guo

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Fred Chang

    Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.

  6. Jawdat Al-Bassam

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    For correspondence
    jawdat@ucdavis.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6625-2102

Funding

National Institutes of Health (GM110283)

  • Jawdat Al-Bassam

National Science Foundation (MCB1615991)

  • Jawdat Al-Bassam

National Institutes of Health (GM115185)

  • Fred Chang

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

Copyright

© 2018, Nithianantham 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. Stanley Nithianantham
  2. Brian D Cook
  3. Madielene Beans
  4. Fei Guo
  5. Fred Chang
  6. Jawdat Al-Bassam
(2018)
Structural basis of tubulin recruitment and assembly by microtubule polymerases with Tumor Overexpressed Gene (TOG) domain arrays
eLife 7:e38922.
https://doi.org/10.7554/eLife.38922

Share this article

https://doi.org/10.7554/eLife.38922

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