Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.
Nat Commun. 2011;2:233. doi: 10.1038/ncomms1215.
Vacuole-type ATPases (V(o)V₁) and F(o)F₁ ATP synthases couple ATP hydrolysis/synthesis in the soluble V(1) or F₁ portion with proton (or Na(+)) flow in the membrane-embedded V(o) or F(o) portion through rotation of one common shaft. Here we show at submillisecond resolutions the ATP-driven rotation of isolated V₁ and the whole V(o)V₁ from Thermus thermophilus, by attaching a 40-nm gold bead for which viscous drag is almost negligible. V₁ made 120° steps, commensurate with the presence of three catalytic sites. Dwells between the steps involved at least two events other than ATP binding, one likely to be ATP hydrolysis. V(o)V₁ exhibited 12 dwell positions per revolution, consistent with the 12-fold symmetry of the V(o) rotor in T. thermophilus. Unlike F₁ that undergoes 80°-40° substepping, chemo-mechanical checkpoints in isolated V₁ are all at the ATP-waiting position, and V(o) adds further bumps through stator-rotor interactions outside and remote from V₁.
空泡型 ATP 酶（V(o)V₁）和 F(o)F₁ ATP 合酶通过一个共同的轴的旋转将可溶性 V(1)或 F₁部分中的 ATP 水解/合成与膜嵌入的 V(o)或 F(o)部分中的质子（或 Na(+)）流动偶联。在这里，我们通过将一个几乎可以忽略粘性阻力的 40nm 金珠附着在分离的 Thermus thermophilus 的 V₁和整个 V(o)V₁上来显示在亚毫秒分辨率下由 ATP 驱动的 V₁和整个 V(o)V₁的旋转。V₁ 进行了 120°的步长，与存在三个催化位点相符。除了 ATP 结合之外，步骤之间的停留至少涉及两个事件，一个可能是 ATP 水解。V(o)V₁每转有 12 个停留位置，与 T. thermophilus 中 V(o)转子的 12 倍对称一致。与经历 80°-40°亚步的 F₁不同，分离的 V₁中的化学机械检查点都在 ATP 等待位置，并且 V(o)通过定子-转子相互作用在 V₁之外和远处增加了进一步的颠簸。
