Nature Structural & Molecular Biology 11, 142 - 148 (2004)
Published online: 18 January 2004 | doi:10.1038/nsmb721
Chemomechanical coupling in F1-ATPase revealed by simultaneous observation of nucleotide kinetics and rotationTakayuki Nishizaka1, 2, 7, Kazuhiro Oiwa1, Hiroyuki Noji3, Shigeki Kimura1, Eiro Muneyuki4, Masasuke Yoshida4, 5
& Kazuhiko Kinosita Jr61 Kansai Advanced Research Center, Protein Biophysics Group, Iwaoka 588-2, Nishi-ku, Kobe 651-2492, Japan. 2 Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan. 3 Institute of Industrial Science, University of Tokyo, Tokyo 153-8505, Japan. 4 Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan. 5 ATP system, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Yokohama 226-0026, Japan. 6 Center for Integrative Bioscience, Okazaki National Research Institutes, Myodaiji, Okazaki 444-8585, Japan. 7 Present address: Department of Physics, Gakushuin University, Mejiro 1-5-1, Toshima-ku, Tokyo 171-8588, Japan.
Correspondence should be addressed to Takayuki Nishizaka takayuki.nishizaka@gakushuin.ac.jpF1-ATPase is a rotary molecular motor in which unidirectional rotation of the central  subunit is powered by ATP hydrolysis in three catalytic sites arranged 120° apart around . To study how hydrolysis reactions produce mechanical rotation, we observed rotation under an optical microscope to see which of the three sites bound and released a fluorescent ATP analog. Assuming that the analog mimics authentic ATP, the following scheme emerges: (i) in the ATP-waiting state, one site, dictated by the orientation of , is empty, whereas the other two bind a nucleotide; (ii) ATP binding to the empty site drives an  80° rotation of ; (iii) this triggers a reaction(s), hydrolysis and/or phosphate release, but not ADP release in the site that bound ATP one step earlier; (iv) completion of this reaction induces further 40° rotation.
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