title: Structural analysis of the transitional state of Arp2/3 complex activation by two actin-bound WCAs.
abstract: Actin filament nucleation and branching by Arp2/3 complex is activated by nucleation-promoting factors (NPFs), whose C-terminal WCA region contains binding sites for actin (W) and Arp2/3 complex (CA). It is debated whether one or two NPFs are required for activation. Here we present evidence in support of the two-NPF model and show that actin plays a crucial role in the interactions of two mammalian NPFs, N-WASP and WAVE2, with Arp2/3 complex. Competition between actin-WCA and glia maturation factor (GMF) for binding to Arp2/3 complex suggests that during activation the first actin monomer binds at the barbed end of Arp2. Based on distance constraints obtained by time-resolved fluorescence resonance energy transfer, we define the relative position of the two actin-WCAs on Arp2/3 complex and propose an atomic model of the 11-subunit transitional complex.
authors: 1] Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 728 Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA [2].
authors: Malgorzata
authors: M
authors: Boczkowska
authors: 1] Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 728 Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA [2].
authors: Grzegorz
authors: G
authors: Rebowski
authors: Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 728 Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA.
authors: David J
authors: DJ
authors: Kast
authors: Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 728 Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA.
authors: Roberto
authors: R
authors: Dominguez
mesh_terms: D051377:Actin-Related Protein 2 / Q000378:metabolism*; D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D051378:Actin-Related Protein 3 / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D031541:Fluorescence Resonance Energy Transfer; D020904:Glia Maturation Factor / Q000378:metabolism; D051379:Mice; D017434:Protein Structure, Tertiary; D051300:Wiskott-Aldrich Syndrome Protein Family / Q000378:metabolism*; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism*
chemical_list: D051377:Actin-Related Protein 2; D051376:Actin-Related Protein 2-3 Complex; D051378:Actin-Related Protein 3; D000199:Actins; D020904:Glia Maturation Factor; D051300:Wiskott-Aldrich Syndrome Protein Family; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal