title: Rotation scheme of V1-motor is different from that of F1-motor.
abstract: V(1), a water-soluble portion of vacuole-type ATPase (V-ATPase), is an ATP-driven rotary motor, similar to F(1)-ATPase. Hydrolysis of ATP is coupled to unidirectional rotation of the central rotor D and F subunits relative to the A(3)B(3) cylinder. In this study, we analyzed the rotation kinetics of V(1) in detail. At low ATP concentrations, the D subunit rotated stepwise, pausing every 120 degrees . The dwell time between steps revealed that V(1) consumes one ATP per 120 degrees step. V(1) generated torque of approximately 35 pN nm, slightly lower than the approximately 46 pN nm measured for F(1). Noticeably, the angles for both ATP cleavage and binding were apparently the same in V(1), in sharp contrast to F(1), which cleaves ATP at 80 degrees posterior to the binding of ATP. Thus, the mechanochemical cycle of V(1) has marked differences to that of F(1).
authors.affiliation: ATP System Project, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Midori-ku, Yokohama.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Imamura
authors.forename: Mizuho
authors.initials: M
authors.lastname: Takeda
authors.forename: Saeko
authors.initials: S
authors.lastname: Funamoto
authors.forename: Katsuya
authors.initials: K
authors.lastname: Shimabukuro
authors.forename: Masasuke
authors.initials: M
authors.lastname: Yoshida
authors.forename: Ken
authors.initials: K
authors.lastname: Yokoyama
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D004926:Escherichia coli; D007700:Kinetics; D020409:Molecular Motor Proteins / Q000378:metabolism / Q000502:physiology*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012399:Rotation; D016963:Thermus thermophilus / Q000201:enzymology*; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism / Q000502:physiology*
chemical_list: D020409:Molecular Motor Proteins; D000255:Adenosine Triphosphate; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases