An alternative reaction pathway of F1-ATPase suggested by rotation without 80°/40° substeps of a sluggish mutant at low ATP
An alternative reaction pathway of F1-ATPase suggested by rotation without 80°/40° substeps of a sluggish mutant at low ATP
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DOI：
10.1529/biophysj.105.067298
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发表时间：
2006-02-01
影响因子：
3.4
通讯作者：
Yoshida, M
中科院分区：
文献类型：
--
作者：
Shimabukuro, K;Muneyuki, E;Yoshida, M
F-1-ATP酶是F0 F1-ATP合成酶的水溶性部分，是由ATP水解驱动的旋转马达。中心γ亚基通过重复四个旋转阶段在α（3）β（3）圆柱体中旋转：ATP结合停留、快速80度子步旋转、催化停留和快速40度子步旋转。在催化停留中，至少发生两个催化反应-酶结合的ATP的切割和推测的水解产物从酶的释放-但是我们发现来自嗜热芽孢杆菌PS3的F-1-ATP酶的缓慢ATP切割突变体在低ATP浓度下旋转，而没有子步骤和催化停留。分析表明，在这个替代反应途径中，两个催化反应发生在前面的长时间ATP结合停留期间。因此，F-1-ATP酶可以通过（至少）两个竞争反应途径，不一定通过简单的连续反应。
F-1-ATPase, a water-soluble portion of F0F1-ATP synthase, is a rotary motor driven by ATP hydrolysis. The central gamma-subunit rotates in the alpha(3)beta(3) cylinder by repeating four stages of rotation: ATP-binding dwell, rapid 80 degrees substep rotation, catalytic dwell, and rapid 40 degrees substep rotation. In the catalytic dwell, at least two catalytic reactions occur-cleavage of the enzyme-bound ATP and presumably release of the hydrolyzed product(s) from the enzyme - but we found that a slow ATP cleavage mutant of F-1-ATPase from thermophilic Bacillus PS3 rotates at low ATP concentration without substeps and the catalytic dwell. Analysis indicates that in this alternative reaction pathway the two catalytic reactions occur during the preceding long ATP-binding dwell. Thus, F-1-ATPase can operate through (at least) two competing reaction pathways, not necessarily through a simple consecutive reaction.