Dresden 2009 – scientific programme
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BP: Fachverband Biologische Physik
BP 9: Actin Dynamics
BP 9.2: Talk
Tuesday, March 24, 2009, 11:00–11:15, ZEU 260
Visco-Elasticity of Actively Deformed Actin Bundles — •Dan Strehle1, Brian Gentry1, Jörg Schnauß1, Mark Bathe2,3, Erwin Frey2, and Josef Käs1 — 1Universität Leipzig — 2LMU München — 3MIT Boston
Actin, a highly conserved cellular protein, forms filamentous polymers under physiological conditions. In vivo these are organized into the networks and bundles that comprise the cytoskeleton, which is responsible for the cell*s morphology and is essential for cell locomotion. Cytoskeletal bundles also perform a variety of additional functions. In filopodia, for instance, they probe the extracellular environment and in stereocilia they serve as the signal transducing organelles of hair cells.
Cells can finely tune the mechanical properties of networks for various tasks by choosing from a variety of actin associated proteins to control growth, crosslinking and bundling of filaments. Dynamic crosslinkers such as alpha-actinin or fascin, for instance, create the possibility for a viscoelastic-like response to different stresses encountered in cellular conditions. This behavior is a well-known property of actin networks, but less is known about time-dependent responses of the bundles themselves.
In order to better characterize the mechanical properties of cytoskeletal F-actin bundles, we have actively deformed reconstituted bundles in vitro. We have seen clear evidence of plastic behavior in which bundles maintain their deformed shape after being bent for an extended time. On shorter holding times they response elastically, returning to their undeformed configurations.