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标题：Catalysis and rotation of F1 motor: Cleavage of ATP at the catalytic site occurs in 1 ms before 40° substep rotation
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作者：Katsuya Shimabukuro ; Ryohei Yasuda ; Eiro Muneyuki 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：25
页码：14731-14736
DOI：10.1073/pnas.2434983100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：F1, a water-soluble portion of FoF1-ATP synthase, is an ATP hydrolysis-driven rotary motor. The central {gamma}-subunit rotates in the 3{beta}3 cylinder by repeating the following four stages of rotation: ATP-binding dwell, rapid 80{degrees} substep rotation, interim dwell, and rapid 40{degrees} 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 F1 subcomplex (3{beta}3{gamma}) from thermophilic Bacillus PS3 under conditions where cleavage of ATP at the catalytic site is decelerated: hydrolysis of ATP by the catalytic-site mutant F1 and hydrolysis of a slowly hydrolyzable substrate ATP{gamma}S (adenosine 5'-[{gamma}-thio]triphosphate) by wild-type F1. 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 ATP{gamma}S hydrolysis by the mutant F1 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 F1 occurs in 1 ms during the interim dwell, and we call this interim dwell catalytic dwell.