The structural basis of actin filament branching by the Arp2/3 complex
AuthorRouiller, I; Xu, X-P; Amann, KJ; Egile, C; Nickell, S; Nicastro, D; Li, R; Pollard, TD; Volkmann, N; Hanein, D
Source TitleThe Journal of Cell Biology
PublisherROCKEFELLER UNIV PRESS
University of Melbourne Author/sRouiller, Isabelle
AffiliationBiochemistry and Molecular Biology
Document TypeJournal Article
CitationsRouiller, I., Xu, X. -P., Amann, K. J., Egile, C., Nickell, S., Nicastro, D., Li, R., Pollard, T. D., Volkmann, N. & Hanein, D. (2008). The structural basis of actin filament branching by the Arp2/3 complex. JOURNAL OF CELL BIOLOGY, 180 (5), pp.887-895. https://doi.org/10.1083/jcb.200709092.
Access StatusOpen Access
The actin-related protein 2/3 (Arp2/3) complex mediates the formation of branched actin filaments at the leading edge of motile cells and in the comet tails moving certain intracellular pathogens. Crystal structures of the Arp2/3 complex are available, but the architecture of the junction formed by the Arp2/3 complex at the base of the branch was not known. In this study, we use electron tomography to reconstruct the branch junction with sufficient resolution to show how the Arp2/3 complex interacts with the mother filament. Our analysis reveals conformational changes in both the mother filament and Arp2/3 complex upon branch formation. The Arp2 and Arp3 subunits reorganize into a dimer, providing a short-pitch template for elongation of the daughter filament. Two subunits of the mother filament undergo conformational changes that increase stability of the branch. These data provide a rationale for why branch formation requires cooperative interactions among the Arp2/3 complex, nucleation-promoting factors, an actin monomer, and the mother filament.
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