The interaction of Arp2/3 complex with actin: Nucleation, high affinity pointed end capping, and formation of branching networks of filaments
Reads0
Chats0
TLDR
It is shown that Arp2/3 complex purified from Acanthamoeba caps the pointed ends of actin filaments with high affinity and increases the critical concentration for polymerization at the pointed end from 0.6 to 1.0 microM.Abstract:
The Arp2/3 complex is a stable assembly of seven protein subunits including two actin-related proteins (Arp2 and Arp3) and five novel proteins. Previous work showed that this complex binds to the sides of actin filaments and is concentrated at the leading edges of motile cells. Here, we show that Arp2/3 complex purified from Acanthamoeba caps the pointed ends of actin filaments with high affinity. Arp2/3 complex inhibits both monomer addition and dissociation at the pointed ends of actin filaments with apparent nanomolar affinity and increases the critical concentration for polymerization at the pointed end from 0.6 to 1.0 μM. The high affinity of Arp2/3 complex for pointed ends and its abundance in amoebae suggest that in vivo all actin filament pointed ends are capped by Arp2/3 complex. Arp2/3 complex also nucleates formation of actin filaments that elongate only from their barbed ends. From kinetic analysis, the nucleation mechanism appears to involve stabilization of polymerization intermediates (probably actin dimers). In electron micrographs of quick-frozen, deep-etched samples, we see Arp2/3 bound to sides and pointed ends of actin filaments and examples of Arp2/3 complex attaching pointed ends of filaments to sides of other filaments. In these cases, the angle of attachment is a remarkably constant 70 ± 7°. From these in vitro biochemical properties, we propose a model for how Arp2/3 complex controls the assembly of a branching network of actin filaments at the leading edge of motile cells.read more
Citations
More filters
Journal ArticleDOI
Cellular Motility Driven by Assembly and Disassembly of Actin Filaments
Thomas D. Pollard,Gary G. Borisy +1 more
TL;DR: A core set of proteins including actin, Arp2/3 complex, profilin, capping protein, and ADF/cofilin can reconstitute the process in vitro, and mathematical models of the constituent reactions predict the rate of motion.
Journal ArticleDOI
Cell mechanics and the cytoskeleton
TL;DR: An important insight emerging from this work is that long-lived cytoskeletal structures may act as epigenetic determinants of cell shape, function and fate.
Journal ArticleDOI
Molecular Mechanisms Controlling Actin Filament Dynamics in Nonmuscle Cells
TL;DR: How motile cells regulate actin filament assembly at their leading edge is reviewed, including how Arp2/3 complex is incorporated into the network, and new filaments are capped rapidly, so that activated Arp1/2 complex must be supplied continuously to keep the network growing.
Journal ArticleDOI
The interaction between N-WASP and the Arp2/3 complex links Cdc42-dependent signals to actin assembly.
Rajat Rohatgi,Le Ma,Hiroaki Miki,Marco Lopez,Tomas Kirchhausen,Tadaomi Takenawa,Marc W. Kirschner +6 more
TL;DR: N-WASP and the Arp2/3 complex comprise a core mechanism that directly connects signal transduction pathways to the stimulation of actin polymerization.
Journal ArticleDOI
Arp2/3 complex and actin depolymerizing factor/cofilin in dendritic organization and treadmilling of actin filament array in lamellipodia.
T.M. Svitkina,Gary G. Borisy +1 more
TL;DR: The leading edge of lamellipodia in Xenopus laevis keratocytes and fibroblasts was shown to have an extensively branched organization of actin filaments, which is supported by a dendritic brush, suggesting that ADF/cofilin, per se, is not sufficient for actin brush depolymerization and a regulatory step is required.
References
More filters
Journal ArticleDOI
Cell motility driven by actin polymerization
Alex Mogilner,George Oster +1 more
TL;DR: It is shown that the thermal motions of the polymerizing filaments can produce a directed force, and this "elastic Brownian ratchet" can explain quantitatively the propulsion of Listeria and the protrusive mechanics of lamellipodia.
Journal ArticleDOI
Actions of cytochalasins on the organization of actin filaments and microtubules in a neuronal growth cone.
Paul Forscher,Stephen J. Smith +1 more
TL;DR: Results suggest that actin normally polymerizes at the leading edge and then flows rearward at a rate between 3-6 microns/min, which is consistent with their being secondary to effects of CB on lamellar F-actin.
Journal ArticleDOI
Rate constants for the reactions of ATP- and ADP-actin with the ends of actin filaments.
TL;DR: I measured the rate of elongation at the barbed and pointed ends of actin filaments by electron microscopy with Limulus sperm acrosomal processes as nuclei to show that the nucleotide composition at or near the end of the growing filament is either the same over this range of growth rates or has no detectable effect on the rate constants.
Journal ArticleDOI
Analysis of the Actin–Myosin II System in Fish Epidermal Keratocytes: Mechanism of Cell Body Translocation
TL;DR: It is proposed that the forward translocation of the cell body and retrograde flow in the lamellipodia are both driven by contraction of an actin–myosin network in the lamplipodial/cell body transition zone.
Journal ArticleDOI
Actin polymerization is induced by Arp2/3 protein complex at the surface of Listeria monocytogenes.
TL;DR: An eight-polypeptide complex is purified that possesses the properties of the host-cell actin polymerization factor and is required to mediate actin tail formation and motility in L. monocytogenes.
Related Papers (5)
Arp2/3 complex and actin depolymerizing factor/cofilin in dendritic organization and treadmilling of actin filament array in lamellipodia.
T.M. Svitkina,Gary G. Borisy +1 more
Cellular Motility Driven by Assembly and Disassembly of Actin Filaments
Thomas D. Pollard,Gary G. Borisy +1 more