Synergy between Wsp1 and Dip1 may initiate assembly of endocytic actin networks

  1. Connor John Balzer
  2. Michael L James
  3. Heidy Y Narvaez-Ortiz
  4. Luke A Helgeson
  5. Vladimir Sirotkin
  6. Brad J Nolen  Is a corresponding author
  1. University of Oregon, United States
  2. Upstate Medical University, United States
  3. University of Washington, United States

Abstract

The actin filament nucleator Arp2/3 complex is activated at cortical sites in S. pombe to assemble branched actin networks that drive endocytosis. Arp2/3 complex activators Wsp1 and Dip1 are required for proper actin assembly at endocytic sites, but how they coordinately control Arp2/3-mediated actin assembly is unknown. Alone, Dip1 activates Arp2/3 complex without preexisting actin filaments to nucleate 'seed' filaments that activate Wsp1-bound Arp2/3 complex, thereby initiating branched actin network assembly. In contrast, because Wsp1 requires pre-existing filaments to activate, it has been assumed to function exclusively in propagating actin networks by stimulating branching from pre-existing filaments. Here we show that Wsp1 is important not only for propagation, but also for initiation of endocytic actin networks. Using single molecule TIRF microscopy we show that Wsp1 synergizes with Dip1 to co-activate Arp2/3 complex. Synergistic coactivation does not require pre-existing actin filaments, explaining how Wsp1 contributes to actin network initiation in cells.

Data availability

All data generated and analyzed in this study have been included in the manuscript and supporting source data files. An individual source data file has been provided for Figures 1, 2, 3 and 4.

Article and author information

Author details

  1. Connor John Balzer

    Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Michael L James

    Cell and Developmental Biology, Upstate Medical University, Syracuse, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Heidy Y Narvaez-Ortiz

    Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Luke A Helgeson

    Department of Biochemistry, University of Washington, Seattle, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5112-2751
  5. Vladimir Sirotkin

    Cell and Developmental Biology, Upstate Medical University, Syracuse, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Brad J Nolen

    Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
    For correspondence
    bnolen@uoregon.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0224-9980

Funding

National Institute of General Medical Sciences (R35GM136319)

  • Brad J Nolen

National Institute of General Medical Sciences (GM007759)

  • Connor John Balzer
  • Luke A Helgeson

American Heart Association (18PRE33960110)

  • Connor John Balzer

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

Reviewing Editor

  1. Alphee Michelot, Institut de Biologie du Développement, France

Version history

  1. Received: June 26, 2020
  2. Accepted: November 10, 2020
  3. Accepted Manuscript published: November 12, 2020 (version 1)
  4. Version of Record published: December 1, 2020 (version 2)

Copyright

© 2020, Balzer 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. Connor John Balzer
  2. Michael L James
  3. Heidy Y Narvaez-Ortiz
  4. Luke A Helgeson
  5. Vladimir Sirotkin
  6. Brad J Nolen
(2020)
Synergy between Wsp1 and Dip1 may initiate assembly of endocytic actin networks
eLife 9:e60419.
https://doi.org/10.7554/eLife.60419

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https://doi.org/10.7554/eLife.60419

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