Abstract
F1-ATPase (F1) is a rotary motor protein that can efficiently convert chemical energy to mechanical work of rotation via fine coordination of its conformational motions and reaction sequences. Compared with reactant binding and product release, the ATP hydrolysis has relatively little contributions to the torque and chemical energy generation. To scrutinize possible roles of ATP hydrolysis, we investigate the detailed statistics of the catalytic dwells from high-speed single wild-type F1 observations. Here we report a small rotation during the catalytic dwell triggered by the ATP hydrolysis that is indiscernible in previous studies. Moreover, we find in freely rotating F1 that ATP hydrolysis is followed by the release of inorganic phosphate with low synthesis rates. Finally, we propose functional roles of the ATP hydrolysis as a key to kinetically unlock the subsequent phosphate release and promote the correct reaction ordering.
Highlights
F1-ATPase (F1) is a rotary motor protein that can efficiently convert chemical energy to mechanical work of rotation via fine coordination of its conformational motions and reaction sequences
We investigate the detailed kinetics of the catalytic dwells and scrutinize the possible roles of the ATP hydrolysis reaction in terms of single F1 rotary observations with microsecond time resolutions and contemporary time series analysis
Model-free change point (CP) and clustering analyses are applied to the angular traces from free rotations of wild-type (WT) F1 derived from thermophilic Bacillus PS3 to robustly construct the statistics of waiting time and angular fluctuations of the catalytic dwells with short duration B1 ms
Summary
F1-ATPase (F1) is a rotary motor protein that can efficiently convert chemical energy to mechanical work of rotation via fine coordination of its conformational motions and reaction sequences. Model-free change point (CP) and clustering analyses are applied to the angular traces from free rotations of wild-type (WT) F1 derived from thermophilic Bacillus PS3 to robustly construct the statistics of waiting time and angular fluctuations of the catalytic dwells with short duration B1 ms. This allows us to detect a small angular increment during the catalytic dwell triggered by the ATP hydrolysis reaction that is indiscernible in previous studies using conventional analysis methods. We propose the functional roles of ATP hydrolysis as a key to accelerate (or kinetically unlock) the subsequent Pi-release reaction and promote the correct reaction ordering, despite its minor contributions to the torque and chemical energy generations
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