Martin James, Hudson Jennifer, Hornung Tassilo, Frasch Wayne D
From the School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501.
From the School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501
J Biol Chem. 2015 Apr 24;290(17):10717-28. doi: 10.1074/jbc.M115.646430. Epub 2015 Feb 24.
Living organisms rely on the FoF1 ATP synthase to maintain the non-equilibrium chemical gradient of ATP to ADP and phosphate that provides the primary energy source for cellular processes. How the Fo motor uses a transmembrane electrochemical ion gradient to create clockwise torque that overcomes F1 ATPase-driven counterclockwise torque at high ATP is a major unresolved question. Using single FoF1 molecules embedded in lipid bilayer nanodiscs, we now report the observation of Fo-dependent rotation of the c10 ring in the ATP synthase (clockwise) direction against the counterclockwise force of ATPase-driven rotation that occurs upon formation of a leash with Fo stator subunit a. Mutational studies indicate that the leash is important for ATP synthase activity and support a mechanism in which residues aGlu-196 and cArg-50 participate in the cytoplasmic proton half-channel to promote leash formation.
生物体依靠F₀F₁ATP合酶来维持ATP与ADP及磷酸之间的非平衡化学梯度，该梯度为细胞过程提供主要能量来源。F₀马达如何利用跨膜电化学离子梯度来产生顺时针扭矩，从而在高ATP水平时克服F₁ATP酶驱动的逆时针扭矩，这是一个尚未解决的主要问题。通过嵌入脂质双层纳米盘中的单个F₀F₁分子，我们现在报告观察到ATP合酶中c₁₀环在与F₀定子亚基a形成束缚时，逆着ATP酶驱动旋转的逆时针力，沿（顺时针）方向进行F₀依赖性旋转。突变研究表明，这种束缚对ATP合酶活性很重要，并支持一种机制，即aGlu-196和cArg-50残基参与细胞质质子半通道以促进束缚的形成。
