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Three‐dimensional reconstructions of Arp2/3 complex with bound nucleation promoting factors
Author(s) -
Xu XiaoPing,
Rouiller Isabelle,
Slaughter Brian D,
Egile Coumaran,
Kim Eldar,
Unruh Jay R,
Fan Xiaoxue,
Pollard Thomas D,
Li Rong,
Hanein Dorit,
Volkmann Niels
Publication year - 2012
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2011.343
Subject(s) - förster resonance energy transfer , protein filament , actin , biophysics , biology , nucleation , actin remodeling , actin binding protein , microbiology and biotechnology , crystallography , fluorescence , actin cytoskeleton , cytoskeleton , biochemistry , chemistry , cell , physics , organic chemistry , quantum mechanics
Arp2/3 complex initiates the growth of branched actin‐filament networks by inducing actin polymerization from the sides of pre‐existing filaments. Nucleation promoting factors (NPFs) are essential for the branching reaction through interactions with the Arp2/3 complex prior to branch formation. The modes by which NPFs bind Arp2/3 complex and associated conformational changes have remained elusive. Here, we used electron microscopy to determine three‐dimensional structures at ∼2 nm resolution of Arp2/3 complex with three different bound NPFs: N‐WASp, Scar‐VCA and cortactin. All of these structures adopt a conformation with the two actin‐related proteins in an actin‐filament‐like dimer and the NPF bound to the pointed end. Distance constraints derived by fluorescence resonance energy transfer independently verified the NPF location. Furthermore, all bound NPFs partially occlude the actin‐filament binding site, suggesting that additional local structural rearrangements are required in the pathway of Arp2/3 complex activation to allow branch formation.