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Title | Cryo-EM structure of NPF-bound human Arp2/3 complex and activation mechanism. |
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Journal, issue, pages | Sci Adv, Vol. 6, Issue 23, Page eaaz7651, Year 2020 |
Publish date | Jun 5, 2020 |
Authors | Austin Zimmet / Trevor Van Eeuwen / Malgorzata Boczkowska / Grzegorz Rebowski / Kenji Murakami / Roberto Dominguez / |
PubMed Abstract | Actin-related protein (Arp) 2/3 complex nucleates branched actin networks that drive cell motility. It consists of seven proteins, including two actin-related subunits (Arp2 and Arp3). Two nucleation- ...Actin-related protein (Arp) 2/3 complex nucleates branched actin networks that drive cell motility. It consists of seven proteins, including two actin-related subunits (Arp2 and Arp3). Two nucleation-promoting factors (NPFs) bind Arp2/3 complex during activation, but the order, specific interactions, and contribution of each NPF to activation are unresolved. Here, we report the cryo-electron microscopy structure of recombinantly expressed human Arp2/3 complex with two WASP family NPFs bound and address the mechanism of activation. A cross-linking assay that captures the transition of the Arps into the activated filament-like conformation shows that actin binding to NPFs favors this transition. Actin-NPF binding to Arp2 precedes binding to Arp3 and is sufficient to promote the filament-like conformation but not activation. Structure-guided mutagenesis of the NPF-binding sites reveals their distinct roles in activation and shows that, contrary to budding yeast Arp2/3 complex, NPF-mediated delivery of actin at the barbed end of both Arps is required for activation of human Arp2/3 complex. |
External links | Sci Adv / PubMed:32548263 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.9 Å |
Structure data | EMDB-20770, PDB-6uhc: |
Chemicals | ChemComp-MG: ChemComp-ATP: |
Source |
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Keywords | CONTRACTILE PROTEIN / actin / ATPase / actin related protein / arp / cytoskeleton / Arp2-3 complex / actin nucleation / actin branching |