Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 23: Cytoskeletal Filaments

BP 23.4: Talk

Thursday, March 29, 2012, 16:00–16:15, H 1028

Formation of regular actin networks as general feature of entropic forces — •Florian Huber, Dan Strehle, Jörg Schnauß, and Josef Käs — Division of Soft Matter Physics, Institute of Experimental Physics I, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany

Biopolymer networks contribute mechanical integrity as well as functional organization to living cells. The protein actin is one of the major constituents of those structures and was found to be present in a large variety of different network architectures ranging from extensive networks to densely packed bundles or fibers.

We developed a reduced experimental bottom-up system to study the formation of confined actin networks by entropic forces. Experiments based on molecular crowding and counterion condensation allow separating mixing effects from cross-linking effects. This reveals a very general tendency of homogeneous filament solutions to aggregate into regular actin bundle networks connected by aster-like centers. Drastic changes in network architecture directly follow from filament ordering or from flow-induced perturbations of the system.

Complemented by coarse-grained modeling the experiments suggest that regular bundle networks might be a rather general feature of isotropic, homogeneous filament solutions subject to uniform attractive interactions. Due to the fundamental nature of the interactions considered, we further expect severe consequences or restrictions to cytoskeletal network formation on the more complex level of living cells.