Chemomechanical coupling in F1-ATPase revealed by simultaneous observation of nucleotide kinetics and rotation
Chemomechanical coupling in F1-ATPase revealed by simultaneous observation of nucleotide kinetics and rotation
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DOI：
10.1038/nsmb721
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发表时间：
2004-02-01
影响因子：
16.8
通讯作者：
Kinosita, K
中科院分区：
文献类型：
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作者：
Nishizaka, T;Oiwa, K;Kinosita, K
f -1-ATP酶是一种旋转分子马达，其中心亚基的单向旋转是由三个催化位点的ATP水解驱动的，这些位点在γ周围相隔120度。为了研究水解反应是如何产生机械旋转的，我们在光学显微镜下观察了旋转，以观察三个位点中哪一个结合并释放了荧光ATP类似物。假设模拟物模拟了真实的ATP，则出现了以下方案：(i)在ATP等待状态下，由方向决定的一个位点是空的，而其他两个位点与核苷酸结合；（ii）与空位点结合的ATP驱动类似于80度的旋转；（iii）这触发了一个反应，水解和/或磷酸盐释放，但不会在先前一步结合ATP的位点释放ADP；（iv）该反应的完成引起进一步的40度旋转。
F-1-ATPase is a rotary molecular motor in which unidirectional rotation of the central subunit is powered by ATP hydrolysis in three catalytic sites arranged 120degrees apart around gamma. To study how hydrolysis reactions produce mechanical rotation, we observed rotation under an optical microscope to see which of the three sites bound and released a fluorescent ATP analog. Assuming that the analog mimics authentic ATP, the following scheme emerges: (i) in the ATP-waiting state, one site, dictated by the orientation of gamma, is empty, whereas the other two bind a nucleotide; (ii) ATP binding to the empty site drives an similar to80degrees rotation of gamma; (iii) this triggers a reaction(s), hydrolysis and/or phosphate release, but not ADP release in the site that bound ATP one step earlier; (iv) completion of this reaction induces further 40degrees rotation.