Structure, rotation and regulation of ATP synthase(FoF1)

我们制备了含有一个或两个突变体的F_1-ATPase。催化动力学发生改变的β亚基。对它们的不对称步进旋转的分析表明，当观看一个时，β亚基在F1-ATPase中，与ATP0°结合，旋转约2 0 0°后裂解，经约32 0°旋转后发生最终催化事件，可能是产物释放。三。β亚基以12 0°差进行这一循环，其区域间的周期性弯曲运动将导致γ亚基的旋转。分子马达F_1-γ酶中心轴ATPase的旋转可能与三种催化剂的区域运动相关，并可能受到这三种催化区域运动的驱动。β亚基。在这里，我们直接观察到这些。β通过连接的荧光团运动，伴随着同一单分子中γ的80度和40度亚步旋转。我们展示了每个β亚基在三步弯曲中经历的构象序列，大约40度逆时针旋转，然后是两个大约20度顺时针旋转，与γ的两个亚步旋转同步发生。结果表明，大多数以前的晶体结构模拟了催化住所中三个β亚基的构象集。此外，在等待三磷酸腺苷的住所中，发现了一组以前未描述的β构象，开放的、关闭的和部分关闭的。因此，本研究在F_1-ATPase的化学步骤和机械步骤之间架起了桥梁。

We made F_1-ATPases containing one or two mutant. β subunits that have the altered catalytic kinetics. The analysis of their asymmetric stepwise rotations reveal that, when watching one. β subunit in F_1-ATPase, it binds ATP at 0°, cleaves ATP after～ 200°rotation, and undergoes the final catalytic event, presumably the product release, after～ 320°rotation. Three. β subunits carry out this cycle at 120°difference like "trolling a tune" and their cyclic inter-domain bending motions would induce the rotation of γ subunit.Rotation of the central shaft γ subunit in a molecular motor F_1-ATPase is assumed to correlate with and probably be driven by domain motions of the three catalytic. β subunits. Here we observe directly these. β motions through an attached fluorophore, concomitantly with 80 degrees and 40 degrees substep rotations of γ in the same single molecules. We show the sequence of conformations that each β subunit undergoes in three-step bending, an approximately 40 degrees counterclockwise turn followed by two approximately 20 degrees clockwise turns, occurring in synchronization with two substep rotations of γ. The results indicate that most previous crystal structures mimic the conformational set of three β subunits in the catalytic dwells. Moreover, a previously undescribed set of β 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.