Coupling of rotation and catalysis in F(1)-ATPase revealed by single-molecule imaging and manipulation.
F(1)-ATPase is a rotary molecular motor that proceeds in 120 degrees steps, each driven by ATP hydrolysis. How the chemical reactions that occur in three catalytic sites are coupled to mechanical rotation is the central question. Here, we show by high-speed imaging of rotation in single molecules of F(1) that phosphate release drives the last 40 degrees of the 120 degrees step, and that the 40 degrees rotation accompanies reduction of the affinity for phosphate. We also show, by single-molecule imaging of a fluorescent ATP analog Cy3-ATP while F(1) is forced to rotate slowly, that release of Cy3-ADP occurs at approximately 240 degrees after it is bound as Cy3-ATP at 0 degrees . This and other results suggest that the affinity for ADP also decreases with rotation, and thus ADP release contributes part of energy for rotation. Together with previous results, the coupling scheme is now basically complete.
Adachi
Kengo
K
Department of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan.
Oiwa
Kazuhiro
K
Nishizaka
Takayuki
T
Furuike
Shou
S
Noji
Hiroyuki
H
Itoh
Hiroyasu
H
Yoshida
Masasuke
M
Kinosita
Kazuhiko
K
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D002384:Catalysis; D021621:Imaging, Three-Dimensional; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012399:Rotation; D013816:Thermodynamics; D013997:Time Factors
D002232:Carbocyanines; D010710:Phosphates; C089187:cyanine dye 3; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases