Mechanik und Dynamik rekonstituierter Aktin-Netzwerke

• Applicants: Professor Dr. Andreas Bausch; Professor Dr. Erwin Frey
• Subject Area: Biophysics ; Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2008 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 86587317

• Final Report Year: 2014

Final Report Abstract

The cytoskeleton consists of only a few types of proteins that are able to assemble into polymeric structures, and a myriad of additional auxiliary proteins which organize these biopolymers in space and time. One of the most prominent cytoskeletal polymers is F-actin, which is essential for numerous cellular functions. Despite decades of thorough investigation, it is far from understood how cells manage to precisely orchestrate their actin cytoskeleton. Even basic principles such as the intrinsic dynamics of actin filaments are still subject of controversial debate. A sound physical understanding of cytoskeletal processes is often impeded by their overwhelming complexity: one major obstacle is the fact that numerous proteins are often simultaneously involved in fulfilling a certain task, which makes it hard to unambiguously identify the function of a particular type of cytoskeletal protein. One way to overcome this dilemma is to study reconstituted in vitro systems, where type and concentration of the proteins as well as the buffer conditions are well defined. This bottom-up approach has already proven useful to study the role of actin cross-linking and bundling proteins. Here we report the results on the statics and dynamics of (i) single actin filaments and (ii) actin bundles, the viscoelasticity of (iii) thermal euqilibrated networks and of (iv) kinetically trapped networks and (v) their nonlinear mechanical properties.

Publications

• Internal stress in kinetically trapped actin bundle networks, Soft Matter, 4, 2365-2367 (2008)
  K.M Schmoller, O. Lieleg, A.R. Bausch
  
• Transient binding and dissipation in crosslinked actin networks, PRL 101, 108101 (2008)
  O. Lieleg, M.M.A.E. Claessens, Y. Luan and A.R. Bausch
  
• Soft Matter, 5, 1796-1803 (2009)
  O. Lieleg, K.M. Schmoller, C.J. Cyron, Y. Luan, W.A. Wall and A.R. Bausch
  
• Structural and Viscoelastic Properties of Actin/Filamin Networks: Cross-linked versus Bundled Networks, Biophys. J., 97, 83-89 (2009)
  K.M Schmoller, O. Lieleg and A.R. Bausch
  
• Tension dynamics and viscoelasticity of extensible wormlike chains, Phys. Rev. E 80, 040801(R) (2009)
  B. Obermayer, E. Frey
  
• Statics and Dynamics of the Wormlike Bundle Model, Phys. Rev. E 81, 021904 (2010)
  C. Heussinger, F. Schüller, and E. Frey
  
• The effect of internal and global modes on the radial distribution function of confined semiflexible polymers, EPL 91 (3) 38004 (2010)
  F. Thüroff, F. Wagner, and E. Frey
  
• Longitudinal Response of Confined Semiflexible Polymers, Phys. Rev. E 83, 021802 (2011)
  F.Thüroff, B. Obermayer, and E. Frey
  
• Cyclic hardening in bundled actin networks, Nat. Comm. 1, 134, (2012)
  K.M. Schmoller, P. Fernandez, R.C. Arevalo, D.L. Blair and A.R. Bausch