Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.63: Poster

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

Proton-driven rotation within the F_0-motor of ATP synthase — •Nawid Zarrabi¹, Monika Düser¹, Dan J. Cipriano², S. Dunn², and Michael Börsch¹ — ¹3. Physikalisches Institut, Universität Stuttgart, Germany — ²Department of Biochemistry, University of Western Ontario, London, Canada

ATP formation by F_0F_1-ATP synthase requires conformational changes that are induced by the stepwise rotation of the ∖gamma and ∖epsilon subunit. The opposite direction of rotation during ATP synthesis and hydrolysis was confirmed by single-molecule fluorescence resonance energy transfer (FRET) [1,2]. Rotation of ∖gamma and ∖epsilon is coupled to the rotation of the $c$ subunits of the ion-driven F_0 motor. ATP hydrolysis resulted in a three-stepped rotation of the $c$-ring of F_0 from a thermophilic bacterium. However, ATP synthesis by the sodium-translocating enzyme from ∖textit{P. modestum} was associated with a multi-stepped rotation. To distinguish between the two mechanisms we have developed a single-molecule FRET assay to monitor the $c$-ring rotation in F_0. Our first data strongly support a stepwise movement of the $c$-ring during ATP synthesis and hydrolysis in contradiction to a quasi-continuous rotation. ∖Zitat{1}{Diez, M., B. Zimmermann, M. Börsch, M. König, E. Schweinberger, S. Steigmiller, R. Reuter, S. Felekyan, V. Kudryavtsev, C.A.M. Seidel, and P. Gräber: Nat. Struct. Mol. Biol. 11:135-142, 2004} ∖Zitat{2}{Zimmermann, B., M. Diez, N. Zarrabi, P. Gräber, and M. Börsch: EMBO J. 24:2053-2063, 2005} ∖Zitat{3}{Düser, M. G., Y. Bi, S. D. Dunn, and M. Börsch: Biochim. Biophys. Acta-Bioenergetics 1658:108 S Supplement, 2004}