Nature Communications | Article Open

Controlled rotation of the F1-ATPase reveals differential and continuous binding changes for ATP synthesis

Kengo Adachi1,6, Kazuhiro Oiwa2, Masasuke Yoshida3,4, Takayuki Nishizaka1, Kazuhiko Kinosita Jr5,
Journal name:  Nature Communications
Volume:  3
Article number:  1022
doi:  10.1038/ncomms2026
Received 
Accepted 
Published

Abstract

F1-ATPase is an ATP-driven rotary molecular motor that synthesizes ATP when rotated in reverse. To elucidate the mechanism of ATP synthesis, we imaged binding and release of fluorescently labelled ADP and ATP while rotating the motor in either direction by magnets. Here we report the binding and release rates for each of the three catalytic sites for 360° of the rotary angle. We show that the rates do not significantly depend on the rotary direction, indicating ATP synthesis by direct reversal of the hydrolysis-driven rotation. ADP and ATP are discriminated in angle-dependent binding, but not in release. Phosphate blocks ATP binding at angles where ADP binding is essential for ATP synthesis. In synthesis rotation, the affinity for ADP increases by > 104, followed by a shift to high ATP affinity, and finally the affinity for ATP decreases by > 104. All these angular changes are gradual, implicating tight coupling between the rotor angle and site affinities.

Affiliations

  1. Department of Physics, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan.
  2. Advanced ICT Research Institute, National Institute of Information and Communications Technology, Nishi-ku, Kobe 651-2492, Japan.
  3. Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan.
  4. ATP-synthesis Regulation Project, International Cooperative Research Project (ICORP), Koto-ku, Tokyo 135-0064, Japan.
  5. Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.
  6. Present address: Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.