Three-color single molecule imaging shows WASP detachment from Arp2/3 complex triggers actin filament branch formation

Benjamin A. Smith, Shae B. Padrick, Lynda K. Doolittle, Karen Daugherty-Clarke, Ivan R. Corrêa, Ming Qun Xu, Bruce L. Goode, Michael K. Rosen, Jeff Gelles

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

During cell locomotion and endocytosis, membrane-tethered WASP proteins stimulate actin filament nucleation by the Arp2/3 complex. This process generates highly branched arrays of filaments that grow toward the membrane to which they are tethered, a conflict that seemingly would restrict filament growth. Using three-color single-molecule imaging in vitro we revealed how the dynamic associations of Arp2/3 complex with mother filament and WASP are temporally coordinated with initiation of daughter filament growth. We found that WASP proteins dissociated from filamentbound Arp2/3 complex prior to new filament growth. Further, mutations that accelerated release of WASP from filament-bound Arp2/3 complex proportionally accelerated branch formation. These data suggest that while WASP promotes formation of pre-nucleation complexes, filament growth cannot occur until it is triggered by WASP release. This provides a mechanism by which membrane-bound WASP proteins can stimulate network growth without restraining it.

Original languageEnglish (US)
Article numbere01008
JournaleLife
Volume2013
Issue number2
DOIs
StatePublished - Sep 3 2013

ASJC Scopus subject areas

  • Neuroscience(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)

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    Smith, B. A., Padrick, S. B., Doolittle, L. K., Daugherty-Clarke, K., Corrêa, I. R., Xu, M. Q., Goode, B. L., Rosen, M. K., & Gelles, J. (2013). Three-color single molecule imaging shows WASP detachment from Arp2/3 complex triggers actin filament branch formation. eLife, 2013(2), [e01008]. https://doi.org/10.7554/eLife.01008