Research Abstract


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

2012年8月28日 Nature Communications 3 : 1022 doi: 10.1038/ncomms2026


足立 健吾1, 大岩 和弘2, 吉田 賢右3,4, 西坂 崇之1 & 木下 一彦5

  1. 学習院大学 理学部物理学科
  2. 情報通信研究機構 未来ICT研究所
  3. 京都産業大学 総合生命科学部 生命システム学科
  4. ATP合成制御プロジェクトInternational Cooperative Research Project (ICORP)
  5. 早稲田大学理工学術院 先進理工学部 物理学科
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.