Deformations in actin comets from rocketing beads.
The mechanical and dynamical properties of the actin network are essential for many cellular processes like motility or division, and there is a growing body of evidence that they are also important for adhesion and trafficking. The leading edge of migrating cells is pushed out by the polymerization of actin networks, a process orchestrated by cross-linkers and other actin-binding proteins. In vitro physical characterizations show that these same proteins control the elastic properties of actin gels. Here we use a biomimetic system of Listeria monocytogenes, beads coated with an activator of actin polymerization, to assess the role of various actin-binding proteins in propulsion. We find that the properties of actin-based movement are clearly affected by the presence of cross-linkers. By monitoring the evolution of marked parts of the comet, we provide direct experimental evidence that the actin gel continuously undergoes deformations during the growth of the comet. Depending on the protein composition in the motility medium, deformations arise from either gel elasticity or monomer diffusion through the actin comet. Our findings demonstrate that actin-based movement is governed by the mechanical properties of the actin network, which are fine-tuned by proteins involved in actin dynamics and assembly.
Paluch
Ewa
E
Laboratoire Physico-Chimie Curie, UMR 168, Institut Curie/Centre National de la Recherche Scientifique/University Paris 6th, Paris, France.
van der Gucht
Jasper
J
Joanny
Jean-François
JF
Sykes
Cécile
C
D051376:Actin-Related Protein 2-3 Complex / Q000737:chemistry; D000199:Actins / Q000737:chemistry*; D001696:Biomechanical Phenomena; D051345:Destrin / Q000737:chemistry; D004058:Diffusion; D004548:Elasticity; D005782:Gels; D018260:Gelsolin / Q000737:chemistry; D008089:Listeria monocytogenes / Q000737:chemistry; D008840:Microfilament Proteins / Q000737:chemistry*; D008863:Microspheres; D008954:Models, Biological; D051304:Profilins / Q000737:chemistry; D051316:Wiskott-Aldrich Syndrome Protein / Q000737:chemistry
D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D051345:Destrin; D005782:Gels; D018260:Gelsolin; D008840:Microfilament Proteins; D051304:Profilins; D051316:Wiskott-Aldrich Syndrome Protein