Characterization of the temperature-sensitive reaction of F1-ATPase by using single-molecule manipulation.
F1-ATPase (F1) is a rotary motor protein that couples ATP hydrolysis to mechanical rotation with high efficiency. In our recent study, we observed a highly temperature-sensitive (TS) step in the reaction catalyzed by a thermophilic F1 that was characterized by a rate constant remarkably sensitive to temperature and had a Q10 factor of 6-19. Since reactions with high Q10 values are considered to involve large conformational changes, we speculated that the TS reaction plays a key role in the rotation of F1. To clarify the role of the TS reaction, in this study, we conducted a stall and release experiment using magnetic tweezers, and assessed the torque generated during the TS reaction. The results indicate that the TS reaction generates the same amount of rotational torque as does ATP binding, but more than that generated during ATP hydrolysis. Thus, we confirmed that the TS reaction contributes significantly to the rotation of F1.
1] Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan [2] PRESTO, JST, Bunkyo-ku, Tokyo 113-8656, Japan.
Rikiya
R
Watanabe
Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
Hiroyuki
H
Noji
D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism*; D012399:Rotation; D013696:Temperature; D019415:Torque
D020409:Molecular Motor Proteins; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases