Conformation changes of actin during formation of filaments and paracrystals and upon interaction with DNase I, cytochalasin B, and phalloidin.

Harwell, O D; Sweeney, Margaret; Kirkpatrick, Francis H.

doi:10.1016/s0021-9258(19)86165-3

Cited by 31 publications

(12 citation statements)

References 57 publications

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“…The small differences in the molecular dimensions of our subunit models and the atomic structure ofthe actin molecule, i.e., 5.5 x -6.0 x -3.2 nm versus 5.5 x 5.5 x 3.5 nm in Kabsch et al . (1990), may primarily be due to conformational changes occurring upon formation of the actin-DNase I complex, or upon polymerization into filaments (Harwell et al, 1980;Holmes et al, 1990;Kabsch et al, 1990). Obviously, some of the differences may also be attributed to specimen preparation artifacts due to surface tension phenomena and the use ofnegative stain .…”

Section: Discussionmentioning

confidence: 99%

The structural basis for the intrinsic disorder of the actin filament: the "lateral slipping" model.

Bremer

Millonig

Sütterlin

et al. 1991

The Journal of Cell Biology

117

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Abstract. Three-dimensional (3-D) helical reconstructions computed from electron micrographs of negatively stained dispersed F-actin filaments invariably revealed two uninterrupted columns of mass forming the "backbone" of the double-helical filament . The contact between neighboring subunits along the thus defined two long-pitch helical strands was spatially conserved and of high mass density, while the intersubunit contact between them was of lower mass density and varied among reconstructions. In contrast, phalloidinstabilized F-actin filaments displayed higher and spatially more conserved mass density between the two long-pitch helical strands, suggesting that this bicyclic hepta-peptide toxin strengthens the intersubunit contact between the two strands. Consistent with this distinct intersubunit bonding pattern, the two long-pitch helical strands of unstabilized filaments were sometimes observed separated from each other over a distance of two to six subunits, suggesting that the intrastrand intersubunit contact is also physically stronger than the interstrand contact. The resolution of the filament reconstructions, extending to 2.5 nm axially and radially, enabled us to reproducibly "cut out" the F-actin subunit which measured 5.5 nm axially by 6.0 nm tangentially by 3.2 nm radially. The subunit is distinctly polar with a massive "base" pointing towards the "barbed" end of the filament, and a slender "tip" ACTIN ranks among the most abundant and highly conserved eukaryotic proteins, and it serves vital functions in muscle contraction, cellular motility, intra cellular transport, and in the regulation of the structure and dynamics of the cytoplasmic matrix . To ensure spatial and temporal control over these diverse functions, actin interacts with itself, with a myriad of actin-binding and regulatory proteins, as well as with small effector molecules (for recent reviews see Pollard, 1990;Vandekerckhove, 1990) .

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Section: Discussionmentioning

confidence: 99%

The structural basis for the intrinsic disorder of the actin filament: the "lateral slipping" model.

Bremer

Millonig

Sütterlin

et al. 1991

The Journal of Cell Biology

117

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“…Nevertheless, major differences exist between the observations of Laliberté et al and the present ones. These authors obtained only actin paracrystals, and single filaments were not seen, suggesting that positive liposomes act like high divalent salt concentrations (Harwell et al, 1980). In addition, polymerization with liposomes follows much faster kinetics and does not lead to apparent defects in the helical symmetry.…”

Section: Assembly and Microscopic Structure Of Surfaceinduced Actin Polymersmentioning

confidence: 96%

“…Despite structural and functional differences between Mg 2ϩ -and Ca 2ϩ -bound forms, Ca 2ϩbound actin does polymerize in solution, but this polymerization requires KCl and shows a long lag phase (Yasuda et al, 1996;Steinmetz et al, 1997). Actin polymerization in solution is classically thought to require the reduction of the net negative charge of the G-actin monomer by salts (Mg 2ϩ , K ϩ ) (Harwell et al, 1980). Here the polymerization of Ca 2ϩ -bound actin is obtained despite the absence of KCl.…”

Section: Assembly and Microscopic Structure Of Surfaceinduced Actin Polymersmentioning

confidence: 99%

Surface-Induced Polymerization of Actin

Renault

Lenne

Zakri

et al. 1999

Biophysical Journal

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Living cells contain a very large amount of membrane surface area, which potentially influences the direction, the kinetics, and the localization of biochemical reactions. This paper quantitatively evaluates the possibility that a lipid monolayer can adsorb actin from a nonpolymerizing solution, induce its polymerization, and form a 2D network of individual actin filaments, in conditions that forbid bulk polymerization. G- and F-actin solutions were studied beneath saturated Langmuir monolayers containing phosphatidylcholine (PC, neutral) and stearylamine (SA, a positively charged surfactant) at PC:SA = 3:1 molar ratio. Ellipsometry, tensiometry, shear elastic measurements, electron microscopy, and dark-field light microscopy were used to characterize the adsorption kinetics and the interfacial polymerization of actin. In all cases studied, actin follows a monoexponential reaction-limited adsorption with similar time constants (approximately 10(3) s). At a longer time scale the shear elasticity of the monomeric actin adsorbate increases only in the presence of lipids, to a 2D shear elastic modulus of mu approximately 30 mN/m, indicating the formation of a structure coupled to the monolayer. Electron microscopy shows the formation of a 2D network of actin filaments at the PC:SA surface, and several arguments strongly suggest that this network is indeed causing the observed elasticity. Adsorption of F-actin to PC:SA leads more quickly to a slightly more rigid interface with a modulus of mu approximately 50 mN/m.

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“…Actin comprises 10% of neutrophil cytoplasmic protein (3) and has two interchangeable physical states with widely different polymerization potentials (4,5). G-actin exists primarily as a monomer due to the high critical concentration required for its polymerization.…”

mentioning

confidence: 99%

“…F-actin has a lower critical polymerization concentration and at the concentration of actin in cytoplasm, oligomers and polymers form. The presence of high concentrations of potassium and magnesium in the cell favors the F-actin conformation (5), whereas, cyto-plasmic proteins such as profilin stabilize G-actin (1,6). Thus, a pool of G-actin monomers exist in equilibrium with F-actin oligomers and polymers.…”

mentioning

confidence: 99%

Chemotactic peptide-induced changes in neutrophil actin conformation.

Wallace¹,

Wersto²,

Packman³

et al. 1984

The Journal of Cell Biology

171

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The effect of the chemotatic peptide, N-formylmethionylleucylphenylalanine (FMLP), on actin conformation in human neutrophils (PMN) was studied by flow cytometry using fluorescent 7-nitrobenz-2-oxa-l,3-diazole (NBD)-phallacidin to quantitate cellular Factin content. Uptake of NBD-phallacidin by fixed PMN was saturable and inhibited by fluid phase F-actin but not G-actin. Stimulation of PMN by >1 nM FMLP resulted in a dosedependent and reversible increase in F-actin in 70-95% of PMN by 30 s. The induced increase in F-actin was blocked by 30 #M cytochalasin B or by a t-BOC peptide that competitively inhibits FMLP binding. Under fluorescence microscopy, NBD-phallacidin stained, unstimulated PMN had faint homogeneous cytoplasmic fluorescence while cells exposed to FMLP for 30 s prior to NBD-phallacidin staining had accentuated subcortical fluorescence. In the continued presence of an initial stimulatory dose of FMLP, PMN could respond with increased F-actin content to the addition of an increased concentration of FMLP. Thus, FMLP binding to PMN induces a rapid transient conversion of unpolymerized actin to subcortical F-actin and repetitive stimulation of F-actin formation can be induced by increasing chemoattractant concentration. The directed movement of PMN in response to chemoattractant gradients may require similar rapid reversible changes in actin conformation.

show abstract

Conformation changes of actin during formation of filaments and paracrystals and upon interaction with DNase I, cytochalasin B, and phalloidin.

Cited by 31 publications

References 57 publications

The structural basis for the intrinsic disorder of the actin filament: the "lateral slipping" model.

The structural basis for the intrinsic disorder of the actin filament: the "lateral slipping" model.

Surface-Induced Polymerization of Actin

Chemotactic peptide-induced changes in neutrophil actin conformation.

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