Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Poster I

BP 7.3: Poster

Monday, March 23, 2009, 17:45–20:00, P3

Diffusion of single actin filaments bound to cationic lipid membranes — •Lydia Woiterski, Florian Rückerl, Josef A. Käs, and Carsten Selle — Institut für Exp. Physik I, Linnéstraße 5, 04103 Leipzig

Actin is one major component of the cytoskeleton in eukaryotic cells. The filaments form a quasi-two-dimensional network - the so-called actin cortex that plays an important role for cell motility. It is associated with the inner leaflet of the cell membrane via protein anchors. Recent studies show that there is a close interplay between the structure of the cytoskeleton and the membrane composition [1]. A model system which mimics the unspecific interactions of cytoskeleton and cellular membranes are actin filaments bound to inhomogeneous lipid membranes. First, the diffusion of single actin filaments adhered to cationic planar membranes will be studied using single polymer tracking. The membranes used are composed of DPPC, DOPC, cholesterol, and the cationic lipid DOTAP and the binding is driven by Manning condensation. Under certain conditions, these liquid membranes show coexistence of ordered and disordered phases. We propose that actin binding can be regulated by the phase state and that preferential binding to one of the coexistent phases occurs due to varied surface charge density. Our aim is a better understanding of how the polymer motion at the membrane can be modulated and the diffusion can be controlled by changing the energy landscape, e.g. by domain sizes and shapes.

1. Kwik, J.et al., PNAS, 2003, 100, p.13964.