Berlin 2008 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 26: Posters II
BP 26.35: Poster
Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A
A Bayesian Approach to 3D Position Determination on the Nanometer Scale by Single-Pair FRET Experiments — •Adam Muschielok1, Joanna Andrecka1, Patrick Cramer1,2, and Jens Michaelis1 — 1Department Chemie und Biochemie, Ludwig-Maximilians-Universität München — 2Gene Center, Ludwig-Maximilians-Universität München
It is often desired to infer the relative position of a domain of a protein/nucleic acid complex that can't be localized by crystallographic means due to its high flexibility. Measurements of distances between two fluorescent dyes based on Fluorescence Resonant Energy Transfer (FRET) can yield this information if one dye molecule (target) is attached to the domain of interest and distance measurements to at least three other dye molecules (anchors) sitting in different but well known positions are carried out. Since the domain of interest is highly flexible, single-molecule measurements are necessary in order to understand the underlying dynamics. We present a new, Bayesian approach to analyze such experiments that is capable of inferring the target dye position and its uncertainty. Based on our measurements, we calculate the probability density distribution of the target dye position and display confidence volumes in the context of crystallographic structure. In contrast to ordinary trilateration this method is able to manage an arbitrarily large number of measurements and accounts for uncertainties in the anchor dye positions, the corresponding Förster radii and the FRET efficiency measurements itself. We apply this method to study yeast RNA polymerase II elongation complexes.