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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Catalysis and rotation of F_1 motor: Cleavage of ATP at the catalytic site occurs in 1 ms before 40° substep rotation
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Catalysis and rotation of F_1 motor: Cleavage of ATP at the catalytic site occurs in 1 ms before 40° substep rotation

机译：F_1电机的催化和旋转：在40°次级旋转之前1毫秒内，催化部位的ATP裂解

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摘要

F_1, a water-soluble portion of F_0F_1-ATP synthase, is an ATP hydrolysis-driven rotary motor. The central γ-subunit rotates in the α_3β_3 cylinder by repeating the following four stages of rotation: ATP-binding dwell, rapid 80° substep rotation, interim dwell, and rapid 40° substep rotation. At least two 1 -ms catalytic events occur in the interim dwell, but it is still unclear which steps in the ATPase cycle, except for ATP binding, correspond to these events. To discover which steps, we analyzed rotations of F_1 subcomplex (α_3β_3γ) from thermophilic Bacillus PS3 under conditions where cleavage of ATP at the catalytic site is decelerated: hydrolysis of ATP by the catalytic-site mutant F_1 and hydrolysis of a slowly hydrolyzable substrate ATPyS (adenosine 5'-[γ-thio]triphosphate) by wild-type F_1. In both cases, interim dwells were extended as expected from bulk phase kinetics, confirming that cleavage of ATP takes place during the interim dwell. Furthermore, the results of ATPγS hydrolysis by the mutant F_1 ensure that cleavage of ATP most likely corresponds to one of the two 1-ms events and not some other faster undetected event. Thus, cleavage of ATP on F_1 occurs in 1 ms during the interim dwell, and we call this interim dwell catalytic dwell.
机译：F_1是F_0F_1-ATP合酶的水溶性部分，是ATP水解驱动的旋转电机。通过重复以下四个旋转阶段，中央γ亚基在α_3β_3圆柱中旋转：ATP绑定驻留，快速80°子步旋转，中间驻留和40°子步快速旋转。至少有两个1 ms的催化事件发生在临时停留中，但是目前尚不清楚除ATP结合以外，ATPase循环中的哪些步骤与这些事件相对应。为了发现哪些步骤，我们分析了在催化位点ATP裂解被减速的条件下，嗜热芽孢杆菌PS3的F_1亚复合物（α_3β_3γ）的旋转：催化位点突变体F_1水解ATP和缓慢水解的底物ATPyS（野生型F_1生成5'-[γ-硫代]三磷酸腺苷）。在这两种情况下，过渡期均按本体相动力学预期的那样延长，这证实了ATP的裂解在过渡期中发生。此外，突变体F_1水解ATPγS的结果确保了ATP的裂解最有可能对应于两个1毫秒事件之一，而不是其他一些更快的未被检测到的事件。因此，在临时停留期间，ATP在F_1上的裂解在1毫秒内发生，我们将此称为临时停留催化停留。

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