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BP: Fachverband Biologische Physik

BP 15: Single-Molecule Biophysics I

BP 15.9: Talk

Tuesday, March 15, 2011, 12:45–13:00, ZEU 250

Tracking single FoF1-ATP synthases in a living E. coli cell — •Marc Renz, Torsten Rendler, Andrea Zappe, Jörg Wrachtrup, and Michael Börsch — 3.Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany

We measured the diffusion of single fluorescence-marked FoF1-ATP synthases in the plasma membrane of living E. coli bacteria. The biological questions of temporary clustering and interactions with other membrane proteins are investigated. We have built a total internal reflection fluorescence microscope for imaging single molecules in Iiving cells. The membrane protein FoF1-ATP synthase has been fluorescently labeled by two different approaches using small fusion proteins. Because of the size (2000 nm x 500 nm) and the shape of the bacterial membranes data analysis of the diffusing proteins is complicated. The algorithm used to extract the Mean Square Displacement (MSD) from the processed raw data will be discussed which allows to calculate a diffusion coefficient. The influence of the finite size of the observation area on the statistics of the measured MSD will be discussed and compared to Monte Carlo simulations.