Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.13: Poster

Mittwoch, 29. März 2006, 16:30–19:30, P3

Supramolecular organization of photosynthetic complexes in model membrane systems — •Tobias Pflock¹, Manuela Dezi², Giovanni Venturoli², Jürgen Köhler¹, and Silke Oellerich¹ — ¹Experimentalphysik IV, Universität Bayreuth, D-95445 Bayreuth — ²Dept. of Biology, University of Bologna, Italy

A common feature of biological membranes is the supramolecular organization of proteins within the membrane to functional units. This process involves a close interaction between the membrane lipids and proteins. Therefore, it is of particular interest to understand the role of lipids for the spatial membrane organization of the proteins. In order to direct this question in a fundamental way, we chose to reconstitute proteins into model membrane systems. This approach allows to sensitively control the membrane lipid composition as well as the lipid-protein ratio. An interesting system for these studies is the photosynthetic unit of purple bacteria, consisting of the reaction centre (RC) and the light-harvesting complexes LH2 and LH1. These pigment-protein complexes organize very efficiently to highly functional units within the natural photosynthetic membrane. The spatial organization of these proteins in model membranes as a function of the membrane composition can be studied by using No-dqGiant unilamellar vesiclesNo-dq (GUV). These vesicles allow a direct observation of protein diffusion and clustering within the membrane by the use of fluorescence wide-field imaging, which can be employed with a sensitivity down to the single-molecule level. For these studies, we succeeded in establishing a protocol for the efficient preparation of GUVs over a wide range of lipid-protein ratios.