Cell, Vol 130, 309-321, 27 July 2007
Article
Coupling of Rotation and Catalysis in F1-ATPase Revealed by Single-Molecule Imaging and Manipulation
1 Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan
2 Kobe
Advanced Research Center, National Institute of Information and
Communications Technology, Nishi-ku, Kobe 651-2492, Japan
3 Department of Physics, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
4 The Institute of Scientific and Industrial Research, Osaka University, Ibaragi, Osaka 567-0047, Japan
5 Tsukuba
Research Laboratory, Hamamatsu Photonics KK, and CREST “Creation and
Application of Soft Nano-Machine, Hyperfunctional Molecular Machine”
Team 13, Tokodai, Tsukuba 300-2635, Japan
6 ATP System Project, Exploratory Research for Advanced Technology (ERATO), Midori-ku, Yokohama 226-0026, Japan
7 Chemical Resources Laboratory, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8503, Japan
Summary
F1-ATPase is a rotary molecular motor that proceeds in 120° steps, each driven by ATP hydrolysis. How the chemical reactions that occur in three catalytic sites are coupled to mechanical rotation is the central question. Here, we show by high-speed imaging of rotation in single molecules of F1 that phosphate release drives the last 40° of the 120° step, and that the 40° rotation accompanies reduction of the affinity for phosphate. We also show, by single-molecule imaging of a fluorescent ATP analog Cy3-ATP while F1 is forced to rotate slowly, that release of Cy3-ADP occurs at ∼240° after it is bound as Cy3-ATP at 0°. This and other results suggest that the affinity for ADP also decreases with rotation, and thus ADP release contributes part of energy for rotation. Together with previous results, the coupling scheme is now basically complete.