An alternative reaction pathway of F1-ATPase suggested by rotation without 80 degrees/40 degrees substeps of a sluggish mutant at low ATP.
F(1)-ATPase, a water-soluble portion of F(o)F(1)-ATP synthase, is a rotary motor driven by ATP hydrolysis. The central gamma-subunit rotates in the alpha(3)beta(3) cylinder by repeating four stages of rotation: ATP-binding dwell, rapid 80 degrees substep rotation, catalytic dwell, and rapid 40 degrees substep rotation. In the catalytic dwell, at least two catalytic reactions occur-cleavage of the enzyme-bound ATP and presumably release of the hydrolyzed product(s) from the enzyme-but we found that a slow ATP cleavage mutant of F(1)-ATPase from thermophilic Bacillus PS3 rotates at low ATP concentration without substeps and the catalytic dwell. Analysis indicates that in this alternative reaction pathway the two catalytic reactions occur during the preceding long ATP-binding dwell. Thus, F(1)-ATPase can operate through (at least) two competing reaction pathways, not necessarily through a simple consecutive reaction.
Shimabukuro
Katsuya
K
ATP System Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency (JST), Yokohama 226-0026, Japan.
Muneyuki
Eiro
E
Yoshida
Masasuke
M
D000255:Adenosine Triphosphate / Q000737:chemistry*; D000818:Animals; D001407:Bacillus / Q000378:metabolism; D019921:Biotinylation; D002384:Catalysis; D002417:Cattle; D049673:History, 20th Century; D006868:Hydrolysis; D007700:Kinetics; D020409:Molecular Motor Proteins; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D012399:Rotation; D012709:Serum Albumin / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
D020409:Molecular Motor Proteins; D012709:Serum Albumin; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases