Dominique Pantaloni

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Actin-binding proteins of the actin depolymerizing factor (ADF)/cofilin family are thought to control actin-based motile processes. ADF1 from Arabidopsis thaliana appears to be a good model that is functionally similar to other members of the family. The function of ADF in actin dynamics has been examined using a combination of physical-chemical methods and(More)
Actin polymerization is essential for cell locomotion and is thought to generate the force responsible for cellular protrusions. The Arp2/3 complex is required to stimulate actin assembly at the leading edge in response to signalling. The bacteria Listeria and Shigella bypass the signalling pathway and harness the Arp2/3 complex to induce actin assembly and(More)
To propel itself in infected cells, the pathogen Shigella flexneri subverts the Cdc42-controlled machinery responsible for actin assembly during filopodia formation. Using a combination of bacterial motility assays in platelet extracts with Escherichia coli expressing the Shigella IcsA protein and in vitro analysis of reconstituted systems from purified(More)
Single actin filaments undergoing brownian movement in two dimensions were observed at 20 degrees C in fluorescence optical video microscopy. The persistence length (Lp) was derived from the analysis of either the cosine correlation function or the average transverse fluctuations of a series of recorded shapes of filaments assembled from rhodamine-action.(More)
Motile and morphogenetic cellular processes are driven by site-directed assembly of actin filaments. Formins, proteins characterized by formin homology domains FH1 and FH2, are initiators of actin assembly. How formins simply bind to filament barbed ends in rapid equilibrium or find free energy to become a processive motor of filament assembly remains(More)
The role of profilin in the regulation of actin assembly has been reexamined. The affinity of profilin for ATP-actin appears 10-fold higher than previously thought. In the presence of ATP, the participation of the profilin-actin complex to filament elongation at the barbed end is linked to a decrease in the steady-state concentration of globular actin. This(More)
Actin polymerization plays a major role in cell movement. The controls of actin sequestration/desequestration and of filament turnover are two important features of cell motility. Actin binding proteins use properties derived from the steady-state monomer-polymer cycle of actin in the presence of ATP, to control the F-actin/G-actin ratio and the turnover(More)
Abiomimetic motility assay is used to analyze the mechanism of force production by site-directed polymerization of actin. Polystyrene microspheres, functionalized in a controlled fashion by the N-WASP protein, the ubiquitous activator of Arp2/3 complex, undergo actin-based propulsion in a medium that consists of five pure proteins. We have analyzed the(More)
We report the use of two independent new methods to measure the flexural rigidity of microtubules. Microtubules were grown off axonemal pieces adhering to a glass coverslip. In the first method, a hydrodynamic flow was applied to microtubules and the flexural rigidity was derived from the analysis of the bending shape of the microtubules at equilibrium in(More)
The mechanism of control of the steady state of actin assembly by actin depolymerizing factor (ADF)/cofilin and profilin has been investigated. Using Tbeta4 as an indicator of the concentration of ATP-G-actin, we show that ADF increases the concentration of ATP-G-actin at steady state. The measured higher concentration of ATP-G-actin is quantitatively(More)