Glia Maturation Factor (GMF) Interacts with Arp2/3 Complex in a Nucleotide State-dependent Manner

Boczkowska, Małgorzata; Rębowski, Grzegorz; Domínguez, Roberto

doi:10.1074/jbc.c113.493338

Cited by 32 publications

(26 citation statements)

References 51 publications

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“…The ADF/cofilin-family member GMF interacts with Arp2/3 complex and promotes debranching 39 . We recently found that GMF interacts very weakly with ATP-Arp2/3 complex but forms a relatively tight 1:1 complex with ADP-Arp2/3 complex 40 . A recent structure of this complex showed that GMF binds at the barbed end of Arp2 41 .…”

Section: Resultsmentioning

confidence: 99%

Structural analysis of the transitional state of Arp2/3 complex activation by two actin-bound WCAs

et al. 2014

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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 conclusive 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 constrains 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.

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Section: Resultsmentioning

confidence: 99%

Structural analysis of the transitional state of Arp2/3 complex activation by two actin-bound WCAs

et al. 2014

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“…However, some experiments point to the Arp2-ARPC1 site as the high-affinity site (26,27,33). For instance, a recent ITC study directly demonstrated that WASP delivers actin monomers to the Arp2 site first, suggesting that, at least in the presence of monomers, the Arp2 site is the higher-affinity site (49). Although the complexity of this issue has precluded a clear consensus, we speculate that the preferred binding site may depend on whether WASP is bound to actin monomers.…”

Section: Discussionmentioning

confidence: 99%

Role and structural mechanism of WASP-triggered conformational changes in branched actin filament nucleation by Arp2/3 complex

Rodnick-Smith

Luan

Liu

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The Arp2/3 (Actin-related proteins 2/3) complex is activated by WASP (Wiskott-Aldrich syndrome protein) family proteins to nucleate branched actin filaments that are important for cellular motility. WASP recruits actin monomers to the complex and stimulates movement of Arp2 and Arp3 into a "short-pitch" conformation that mimics the arrangement of actin subunits within filaments. The relative contribution of these functions in Arp2/3 complex activation and the mechanism by which WASP stimulates the conformational change have been unknown. We purified budding yeast Arp2/3 complex held in or near the short-pitch conformation by an engineered covalent cross-link to determine if the WASP-induced conformational change is sufficient for activity. Remarkably, cross-linked Arp2/3 complex bypasses the need for WASP in activation and is more active than WASP-activated Arp2/3 complex. These data indicate that stimulation of the short-pitch conformation is the critical activating function of WASP and that monomer delivery is not a fundamental requirement for nucleation but is a specific requirement for WASP-mediated activation. During activation, WASP limits nucleation rates by releasing slowly from nascent branches. The cross-linked complex is inhibited by WASP's CA region, even though CA potently stimulates cross-linking, suggesting that slow WASP detachment masks the activating potential of the short-pitch conformational switch. We use structure-based mutations and WASP-Arp fusion chimeras to determine how WASP stimulates movement toward the short-pitch conformation. Our data indicate that WASP displaces the autoinhibitory Arp3 C-terminal tail from a hydrophobic groove at Arp3′s barbed end to destabilize the inactive state, providing a mechanism by which WASP stimulates the short-pitch conformation and activates Arp2/3 complex.actin | Arp2/3 | WASP

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“…The mechanism of branch dissociation is not fully understood, but a combination of dissociation of the Arp2/3 complex from the mother filament and/or from the pointed end of the daughter filaments has been proposed (25,52,189). Another member of the ADF/cofilin superfamily, glia maturation factor (GMF), targets the junction between actin subunits and the Arp2/3 complex of the daughter filament, dismantling branch points and inhibiting new actin assembly (31,97,182,347). This microscopic effect of ADF/cofilin family proteins on the stability of Arp2/3 complex branch stability can be observed at the larger scale of dense branched networks reconstituted in vitro (FIGURE 4D).…”

Section: Adf/cofilin-induced Disassemblymentioning

confidence: 99%

Actin Dynamics, Architecture, and Mechanics in Cell Motility

Blanchoin

Boujemaa-Paterski

Sykes

et al. 2014

Physiological Reviews

1,197

1,145

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Tight coupling between biochemical and mechanical properties of the actin cytoskeleton drives a large range of cellular processes including polarity establishment, morphogenesis, and motility. This is possible because actin filaments are semi-flexible polymers that, in conjunction with the molecular motor myosin, can act as biological active springs or "dashpots" (in laymen's terms, shock absorbers or fluidizers) able to exert or resist against force in a cellular environment. To modulate their mechanical properties, actin filaments can organize into a variety of architectures generating a diversity of cellular organizations including branched or crosslinked networks in the lamellipodium, parallel bundles in filopodia, and antiparallel structures in contractile fibers. In this review we describe the feedback loop between biochemical and mechanical properties of actin organization at the molecular level in vitro, then we integrate this knowledge into our current understanding of cellular actin organization and its physiological roles. I. PREFACE ON ACTIN ORGANIZATION AND CELL MECHANICSAnimal cells (i.e., those without a cell wall) have the ability to change their shape to adapt to their environment, move through narrow spaces, divide, or allow exo-and endocytosis. The machinery of these shape changes relies on the assembly of proteins, in particular actin, a globular protein that polymerizes into filaments of different types of organization: branched and crosslinked networks, parallel bundles, and anti-parallel contractile structures (FIGURE 1A). These different architectures can be envisioned as a series of interconnected active springs and dashpots (green and red symbols in FIGURE 1B, respectively) that act as mechanical elements to drive cell shape changes and motility. The purpose of this review is to correlate recent progress in our understanding of the interplay between biochemical elements and mechanical properties. Instead of describing biochemical and mechanical properties separately, our main goal here is to address piece by piece the integrated feedback loop between biochemistry and mechanics.At the front of the cell, branched and crosslinked networks in a quasi two-dimensional sheet make up the lamellipodium, and are the major engine of cell movement since they push the cell membrane by polymerizing against it (FIGURE 1A, iii). Aligned bundles underlie filopodia that are the fingerlike structures at the front of the cell, important for directional response of the cell (FIGURE 1A, iv). A thin layer of actin, called the cell cortex, coats the plasma membrane at the back and sides of the cell, important for cell shape maintenance and changes (FIGURE 1A, i). The rest of the cell contains a three-dimensional network of crosslinked filaments interspersed with contractile bundles, including stress fibers that connect the cell cytoskeleton to the extracellular matrix via focal adhesion sites (FIGURE 1A, ii). Contraction in the cell is produced by the molecular motor protein myosin. Myosin assembles into anti...

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Glia Maturation Factor (GMF) Interacts with Arp2/3 Complex in a Nucleotide State-dependent Manner

Cited by 32 publications

References 51 publications

Structural analysis of the transitional state of Arp2/3 complex activation by two actin-bound WCAs

Structural analysis of the transitional state of Arp2/3 complex activation by two actin-bound WCAs

Role and structural mechanism of WASP-triggered conformational changes in branched actin filament nucleation by Arp2/3 complex

Actin Dynamics, Architecture, and Mechanics in Cell Motility

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