Berlin 2005 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 100: Poster Session I
AKB 100.26: Poster
Samstag, 5. März 2005, 16:45–18:45, Poster TU D
ROTATION AND CONFORMATIONAL CHANGES OF THE EPSILON SUBUNIT OF F0F1-ATP SYNTHASE — •Marc Karle1, Boris Zimmermann2, Nawid Zarrabi1, Monika Düser1, Jörg Wrachtrup1, and Michael Börsch1 — 13. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart — 2Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 23a, 79104 Freibrug
Cellular ATP production is catalysed by membrane-bound F0F1-ATP synthase. An internal rotation of subunits couples the chemical reaction at three binding sites in the F1 part to proton translocation through the membrane-integrated F0 part. We apply single-molecule fluorescence resonance energy transfer (FRET) to examine the rotary subunit movements. Rotation is divided into three major steps with constant FRET level corresponding to three relative orientations (M. Diez et al. 2004 Nat Struct Mol Biol 11, 135). For epsilon-subunit rotation we have found distinct dwell times for the three different orientations, indicating heterogeneous catalytic rates at the three binding sites (M. Börsch et al. 2004 Biophys J 86, 181A, Part 2 Suppl). To support our single-molecule FRET analysis and to evaluate the statistical significance of the data set we also develop computer simulations of the signals, that help to unravel critical parameters. These simulations strongly support the non-equal catalytic rates.