Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 19: Semiflexible Polymers and Networks

BP 19.5: Talk

Wednesday, February 27, 2008, 18:30–18:45, PC 203

Accessory contribution of actin binding proteins to the viscoelastic properties of composite actin-networks — •Kurt Schmoller, Oliver Lieleg, and Andreas Bausch — Lehrstuhl E22 für Biophysik, Physik Department, TU München, Garching, Deutschland

Cell shape, mechanics and motility are mainly determined by crosslinked and bundled actin-networks. As in living cells many different actin binding proteins (ABPs) are used simultaneously, it is necessary to study their mechanical function in well-defined in vitro systems where the type and concentration of the ABP can be controlled. By rheological methods we determine the viscoelastic properties of bundled and crosslinked actin networks. The ABPs filamin and fascin are both known to bundle actin filaments. However, the bundle networks formed exhibit pronounced differences in their viscoelastic properties. We investigate composite networks tuning the concentration of either fascin or filamin in the presence of the other ABP. Interestingly, the concentration dependence of the viscoelastic network response is only slightly modified by the presence of the second ABP. These findings suggest that a combination of these two ABPs does not lead to a phase separation, but to an accessory contribution to the viscoelastic properties of the composite network. Further we find networks with a frequency response resembling that of living cells. These findings underline that in vitro actin networks with only a few combined ABPs might be sufficient to rationalize main aspects of the mechanical properties of cells.