1] Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan [2] PRESTO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.
Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
Sci Rep. 2014 May 14;4:4962. doi: 10.1038/srep04962.
F1-ATPase (F1) is a rotary motor protein that couples ATP hydrolysis to mechanical rotation with high efficiency. In our recent study, we observed a highly temperature-sensitive (TS) step in the reaction catalyzed by a thermophilic F1 that was characterized by a rate constant remarkably sensitive to temperature and had a Q10 factor of 6-19. Since reactions with high Q10 values are considered to involve large conformational changes, we speculated that the TS reaction plays a key role in the rotation of F1. To clarify the role of the TS reaction, in this study, we conducted a stall and release experiment using magnetic tweezers, and assessed the torque generated during the TS reaction. The results indicate that the TS reaction generates the same amount of rotational torque as does ATP binding, but more than that generated during ATP hydrolysis. Thus, we confirmed that the TS reaction contributes significantly to the rotation of F1.
F1-ATP 合酶（F1）是一种旋转分子马达，能够高效地将 ATP 水解与机械旋转偶联。在我们最近的研究中，我们观察到一种嗜热 F1 催化的反应中存在一个高度热敏（TS）步骤，其特征是速率常数对温度非常敏感，Q10 因子为 6-19。由于具有高 Q10 值的反应被认为涉及大的构象变化，我们推测 TS 反应在 F1 的旋转中起着关键作用。为了阐明 TS 反应的作用，在本研究中，我们使用磁镊进行了停顿和释放实验，并评估了 TS 反应过程中产生的扭矩。结果表明，TS 反应产生的旋转扭矩与 ATP 结合时相同，但大于 ATP 水解时产生的扭矩。因此，我们证实 TS 反应对 F1 的旋转有重要贡献。
