Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Posters I

BP 7.42: Poster

Monday, February 25, 2008, 17:00–19:30, Poster A

Diffusion of single actin filaments bound to cationic model membranes — •Lydia Woiterski, Florian Rückerl, Josef Käs, and Carsten Selle — Universität Leipzig, Physik Weicher Materie, Linnéstr. 5, 04103 Leipzig

Actin is one of major components 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 motility and adhesion. It is associated with the inner leaflet of the cell membrane via protein anchors and was suggested to control protein motion. Thus, it is of great interest to elucidate the nature of interaction of polymerized actin and lipid membrane models. In previous work it was reported that binding of filamentous actin to cationic lipid membranes is governed by Coulomb interactions [Sengupta et al. 2006]. 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. First, the binding process of F-actin is studied using giant vesicles prepared from mixtures of phosphatidylcholine, the cationic lipid DOTAP, and cholesterol that adsorb actin filaments which is monitored by fluorescence microscopy. Secondly, the diffusion of single actin filaments adsorbed to supported bilayers is investigated by single polymer tracking in order to study how the domains confine the lateral motion of the polymer.

[1] Sengupta, K., E.Sackmann, et al. (2006), Langmuir 22(13): 5776.