Cooperative three-step motions in catalytic subunits of F1-ATPase correlate with 80° and 40° substep rotations
Cooperative three-step motions in catalytic subunits of F1-ATPase correlate with 80° and 40° substep rotations
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DOI：
10.1038/nsmb.1510
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发表时间：
2008-12-01
影响因子：
16.8
通讯作者：
Nishizaka, Takayuki
中科院分区：
文献类型：
--
作者：
Masaike, Tomoko;Koyama-Horibe, Fumie;Nishizaka, Takayuki
分子马达f -1- atp酶中轴γ亚基的旋转被认为与三个催化β亚基的结构域运动有关，并可能由其驱动。在这里，我们通过附着的荧光团直接观察到这些b的运动，同时在同一单个分子中c的80度和40度亚阶旋转。我们展示了每个b亚基在三步弯曲中经历的构象序列，类似于40度逆时针旋转，然后是两个类似于20度顺时针旋转，与伽马的两个子步旋转同步发生。结果表明，大多数先前的晶体结构模拟了催化孔中三个b亚基的构象集。此外，先前描述的一组β构象，开放的，封闭的和部分封闭的，在atp等待结构中被揭示。因此，目前的研究弥合了f -1- atp酶的化学和机械步骤之间的差距。
Rotation of the central shaft gamma subunit in a molecular motor F-1-ATPase is assumed to correlate with and probably be driven by domain motions of the three catalytic beta subunits. Here we observe directly these b motions through an attached fluorophore, concomitantly with 80 degrees and 40 degrees substep rotations of c in the same single molecules. We show the sequence of conformations that each b subunit undergoes in three-step bending, a similar to 40 degrees counterclockwise turn followed by two similar to 20 degrees clockwise turns, occurring in synchronization with two substep rotations of gamma. The results indicate that most previous crystal structures mimic the conformational set of three b subunits in the catalytic dwells. Moreover, a previously undescribed set of beta conformations, open, closed and partially closed, is revealed in the ATP-waiting dwells. The present study thus bridges the gap between the chemical and mechanical steps in F-1-ATPase.