F0F1-ATPase/synthase is geared to the synthesis mode by conformational rearrangement of epsilon subunit in response to proton motive force and ADP/ATP balance.
The epsilon subunit in F0F1-ATPase/synthase undergoes drastic conformational rearrangement, which involves the transition of two C-terminal helices between a hairpin "down"-state and an extended "up"-state, and the enzyme with the up-fixed epsilon cannot catalyze ATP hydrolysis but can catalyze ATP synthesis (Tsunoda, S. P., Rodgers, A. J. W., Aggeler, R., Wilce, M. C. J., Yoshida, M., and Capaldi, R. A. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 6560-6564). Here, using cross-linking between introduced cysteine residues as a probe, we have investigated the causes of the transition. Our findings are as follows. (i) In the up-state, the two helices of epsilon are fully extended to insert the C terminus into a deeper position in the central cavity of F1 than was thought previously. (ii) Without a nucleotide, epsilon is in the up-state. ATP induces the transition to the down-state, and ADP counteracts the action of ATP. (iii) Conversely, the enzyme with the down-state epsilon can bind an ATP analogue, 2',3'-O-(2,4,6-trinitrophenyl)-ATP, much faster than the enzyme with the up-state epsilon. (iv) Proton motive force stabilizes the up-state. Thus, responding to the increase of proton motive force and ADP, F0F1-ATPase/synthase would transform the epsilon subunit into the up-state conformation and change gear to the mode for ATP synthesis.
Suzuki
Toshiharu
T
ATP System Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Corporation (JST), Nagatsuta 5800-2, Yokohama 226-0026, Japan.
Murakami
Tomoe
T
Iino
Ryota
R
Suzuki
Junko
J
Ono
Sakurako
S
Shirakihara
Yasuo
Y
Yoshida
Masasuke
M
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002384:Catalysis; D029968:Escherichia coli Proteins / Q000737:chemistry; D020409:Molecular Motor Proteins / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D011506:Proteins / Q000737:chemistry; D018892:Proton-Motive Force; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism; D000097795:ATPase Inhibitory Protein
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D029968:Escherichia coli Proteins; D020409:Molecular Motor Proteins; D021122:Protein Subunits; D011506:Proteins; D006180:Proton-Translocating ATPases; D000097795:ATPase Inhibitory Protein