Dresden 2006 – scientific programme
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AKB: Biologische Physik
AKB 3: Cell Motility I
AKB 3.1: Invited Talk
Monday, March 27, 2006, 11:30–12:00, ZEU 255
Symmetry Breaking and Elastic Deformations drive Actin-Based Movement — •Ewa Paluch1,2, Jasper van der Gucht1, Jean-François Joanny1, and Cécile Sykes1 — 1Institut Curie/CNRS, UMR 168, 26 rue d’Ulm, 75005 Paris, France — 2Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
Cells move and change shape by means of the cytoskeleton, an active gel made of polar filaments such as actin. The filaments themselves are highly dynamic and continuously polymerize and depolymerize using chemical energy. Bacterial pathogens such as Listeria monocytogenes have been shown to hijack the actin polymerization machinery inside cells in order to propel themselves forward. This mechanism is often studied using beads, which polymerize on their surface an actin gel that spontaneously polarizes and gives rise to an actin comet that propels the bead forward.
We use a simple assay composed of purified commercial proteins to study the symmetry breaking event that precedes movement. We show that gel breakage results from a release of elastic energy and propose a model based on the theory of fracture in polymer gels. Moreover we provide direct evidence that the actin gel in the comet continues to deform even after symmetry breaking. We propose a model that accounts for these deformations, where the comet is considered as an elastic fluid.