Adachi Kengo, Oiwa Kazuhiro, Nishizaka Takayuki, Furuike Shou, Noji Hiroyuki, Itoh Hiroyasu, Yoshida Masasuke, Kinosita Kazuhiko
Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.
Cell. 2007 Jul 27;130(2):309-21. doi: 10.1016/j.cell.2007.05.020.
F(1)-ATPase is a rotary molecular motor that proceeds in 120 degrees 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 F(1) that phosphate release drives the last 40 degrees of the 120 degrees step, and that the 40 degrees rotation accompanies reduction of the affinity for phosphate. We also show, by single-molecule imaging of a fluorescent ATP analog Cy3-ATP while F(1) is forced to rotate slowly, that release of Cy3-ADP occurs at approximately 240 degrees after it is bound as Cy3-ATP at 0 degrees . 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.
F(1)-ATP酶是一种旋转分子马达，以120度步幅前进，每一步都由ATP水解驱动。三个催化位点发生的化学反应如何与机械旋转相耦合是核心问题。在此，我们通过对F(1)单分子旋转的高速成像表明，磷酸释放驱动了120度步幅中的最后40度，并且这40度旋转伴随着对磷酸亲和力的降低。我们还通过在F(1)被迫缓慢旋转时对荧光ATP类似物Cy3-ATP进行单分子成像表明，Cy3-ADP在0度以Cy3-ATP形式结合后约240度时释放。这一结果以及其他结果表明，对ADP的亲和力也随着旋转而降低，因此ADP释放为旋转贡献了部分能量。与之前的结果一起，耦合机制现在基本完整。
