A simple model for the cooperative stabilisation of actin filaments by phalloidin and jasplakinolide

Visegrády, Balázs; Lőrinczy, D.; Hild, Gábor; Somogyi, B; Nyitrai, Miklós

doi:10.1016/j.febslet.2004.11.023

Cited by 67 publications

(65 citation statements)

References 29 publications

(37 reference statements)

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“…To approximate the contribution of these peaks to the heat absorption curves, we applied Gaussian fits. We applied a similar approach successfully in a previous study for the analysis of complex DSC curves (26). The contribution of the lower-and higher-temperature transitions in the DSC curves was quantified by determining the integral of the corresponding Gaussian curves (under-curve areas).…”

Section: Lack Of Cooperativity In Adpbef X -And Adpalf 4 -Actin Filmentioning

confidence: 99%

“…Thus, 1 -p is the probability that an actin protomer does not bind phalloidin. The value of k can be determined by fitting eq 1 to the experimental data, and then the number of actin protomers affected by one phalloidin molecule is calculated to be 2k + 1 (26).…”

Section: Dsc Measurementsmentioning

confidence: 99%

“…The second heating measurement indicated full irreversible denaturation of the actin during the first run. We applied the model described recently (26) to analyze the phalloidin concentration dependence of the DSC data obtained with actin filaments and to define the degree of cooperativity along the filaments. The model assumes that phalloidin can stabilize the conformation of the protomer to which it is bound.…”

Section: Dsc Measurementsmentioning

confidence: 99%

“…Previous studies have shown that the binding of phalloidin stabilizes the structure of actin filaments (27)(28)(29)(30)(31)(32)(33) and one bound phalloidin can stabilize seven neighboring protomers (26). In this work, we characterize the effect of phalloidin on the thermal stability of actin filaments in complex with different nucleotide analogues (ADP.BeF x or ADP.AlF 4 ) by using differential scanning calorimetry (DSC).…”

mentioning

confidence: 99%

“…In a special case, it was proposed that cooperative interactions could play an important role in the regulation of muscle contraction (25). We suggested recently that the cooperative behavior of actin filaments could provide the structural bases for information channels in living cells, through which the different actinbinding effectors can express their full effect even under substoichiometric binding conditions (26).…”

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Noncooperative Stabilization Effect of Phalloidin on ADP.BeF_x- and ADP.AlF₄-Actin Filaments

et al. 2008

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Actin plays important roles in eukaryotic cell motility. During actin polymerization, the actinbound ATP is hydrolyzed to ADP and P i . We carried out differential scanning calorimetry experiments to characterize the cooperativity of the stabilizing effect of phalloidin on actin filaments in their ADP.P i state. The ADP.P i state was mimicked by using ADP.BeF x or ADP.AlF 4 . The results showed that the binding of the nucleotide analogues or phalloidin stabilized the actin filaments to a similar extent when added separately. Phalloidin binding to ADP.BeF x -or ADP.AlF 4 -actin filaments further stabilized them, indicating that the mechanism by which phalloidin and the nucleotide analogues affect the filament structure was different. The results also showed that the stabilization effect of phalloidin binding to ADP.BeF x or ADP.AlF 4 -bound actin filaments was not cooperative. Since the effect of phalloidin binding was cooperative in the absence of these nucleotide analogues, these results suggest that the binding of ADP.BeF x or ADP.AlF 4 to the actin modified the protomer-protomer interactions along the actin filaments.Actin is one of the main components of the cytoskeleton and plays important roles in the motility of eukaryotic cells (1-7). The actin monomer can bind a nucleotide in complex with a divalent cation in the cleft between the two main domains of the protein (Figure 1) (8). During polymerization, the ATP is hydrolyzed to ADP and P i 1 (9-16). The ADP.P i state is transient as the inorganic phosphate product is released from actin after polymerization. For † This study was supported by grants from the Hungarian Scientific Research Fund [OTKA Grants K60186 and K60968 (M.Ny.)]. The SETARAM Micro DSC-II instrument was purchased with a grant MATERIALS AND METHODS ChemicalsKCl, MgCl 2 , CaCl 2 , MOPS, EGTA, AlCl 3 , and NaF were purchased from SIGMA-Aldrich (Budapest, Hungary). ATP, ADP, and β-mercaptoethanol were obtained from MERCK (Darmstadt, Germany). NaN 3 and BeSO 4 were purchased from Fluka (St. Gallen, Switzerland). Protein PreparationSkeletal actin was prepared from acetone powder obtained from rabbit muscle (12,34). After purification, the calcium-bound actin monomers were stored in a 2 mM MOPS buffer (pH 7.3) with 0.2 mM ATP, 0.1 mM CaCl 2 , 0.1 mM β-mercaptoethanol, and 0.005% NaN 3 .The actin monomer concentration was determined by absorption photometry using 0.63 mg −1 mL cm −1 as the extinction coefficient at 290 nm (35). Actin-bound calcium was exchanged for magnesium by incubating the samples with 0.2 mM EGTA and 0.1 mM MgCl 2 for 5 min (36). Actin polymerization was initiated by the addition of 2 mM MgCl 2 and 100 mM KCl. ADP.BeF x -actin filaments were prepared in a similar way as described by Levitsky and colleagues (37); BeSO 4 (0.03-3 mM) and NaF (0.1-10 mM) were added to the samples, and actin was polymerized at room temperature for 3 h. Note that since the presence of ADP, BeSO 4 , and NaF in the solution leads to formation of either ADP.BeF 2 (OH) -•H 2 O or ADP.BeF 3 -...

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Section: Lack Of Cooperativity In Adpbef X -And Adpalf 4 -Actin Filmentioning

confidence: 99%

Section: Dsc Measurementsmentioning

confidence: 99%

Section: Dsc Measurementsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Noncooperative Stabilization Effect of Phalloidin on ADP.BeF_x- and ADP.AlF₄-Actin Filaments

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Conformational dynamics of actin: Effectors and implications for biological function

2010

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Actin is a protein abundant in many cell types. Decades of investigations have provided evidence that it has many functions in living cells. The diverse morphology and dynamics of actin structures adapted to versatile cellular functions is established by a large repertoire of actin-binding proteins. The proper interactions with these proteins assume effective molecular adaptations from actin, in which its conformational transitions play essential role. This review attempts to summarise our current knowledge regarding the coupling between the conformational states of actin and its biological function.

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Stabilization of actin filaments prevents germinal vesicle breakdown and affects microtubule organization in Xenopus oocytes

et al. 2012

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In Xenopus oocytes, extremely giant nuclei, termed germinal vesicles, contain a large amount of actin filaments most likely for mechanical integrity. Here, we show that microinjection of phalloidin, an F-actin-stabilizing drug, prevents the germinal vesicle breakdown (GVBD) in oocytes treated with progesterone. These nuclei remained for more 12 h after control oocytes underwent GVBD. Immunostaining showed significant elevation of actin in the remaining nuclei and many actin filament bundles in the cytoplasm. Furthermore, microtubules formed unusual structures in both nuclei and cytoplasm of phalloidin-injected oocytes stimulated by progesterone. Cytoplasmic microtubule arrays and intranuclear microtubules initially formed in phalloidin-injected oocytes as control oocytes exhibited white maturation spots; these structures gradually disappeared and finally converged upon intranuclear short bundles when control oocytes completed maturation. In contrast, treatment of oocytes with jasplakinolide, a cell membrane-permeable actin filament-stabilizing drug, did not affect GVBD. This drug preferentially induced accumulation of actin filaments at the cortex without any increase in cytoplasmic actin staining. Based on these results, intranuclear and cytoplasmic actin filament dynamics appear to be required for the completion of GVBD and critically involved in the regulation of microtubule assembly during oocyte maturation in Xenopus laevis.

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A simple model for the cooperative stabilisation of actin filaments by phalloidin and jasplakinolide

Cited by 67 publications

References 29 publications

Noncooperative Stabilization Effect of Phalloidin on ADP.BeF_x- and ADP.AlF₄-Actin Filaments

Noncooperative Stabilization Effect of Phalloidin on ADP.BeF_x- and ADP.AlF₄-Actin Filaments

Conformational dynamics of actin: Effectors and implications for biological function

Stabilization of actin filaments prevents germinal vesicle breakdown and affects microtubule organization in Xenopus oocytes

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A simple model for the cooperative stabilisation of actin filaments by phalloidin and jasplakinolide

Cited by 67 publications

References 29 publications

Noncooperative Stabilization Effect of Phalloidin on ADP.BeFx- and ADP.AlF4-Actin Filaments

Noncooperative Stabilization Effect of Phalloidin on ADP.BeFx- and ADP.AlF4-Actin Filaments

Conformational dynamics of actin: Effectors and implications for biological function

Stabilization of actin filaments prevents germinal vesicle breakdown and affects microtubule organization in Xenopus oocytes

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Noncooperative Stabilization Effect of Phalloidin on ADP.BeF_x- and ADP.AlF₄-Actin Filaments

Noncooperative Stabilization Effect of Phalloidin on ADP.BeF_x- and ADP.AlF₄-Actin Filaments