title: Torque generation mechanism of F1-ATPase upon NTP binding.
abstract: Molecular machines fueled by NTP play pivotal roles in a wide range of cellular activities. One common feature among NTP-driven molecular machines is that NTP binding is a major force-generating step among the elementary reaction steps comprising NTP hydrolysis. To understand the mechanism in detail,in this study, we conducted a single-molecule rotation assay of the ATP-driven rotary motor protein F1-ATPase using uridine triphosphate (UTP) and a base-free nucleotide (ribose triphosphate) to investigate the impact of a pyrimidine base or base depletion on kinetics and force generation. Although the binding rates of UTP and ribose triphosphate were 10(3) and 10(6) times, respectively, slower than that of ATP, they supported rotation, generating torque comparable to that generated by ATP. Affinity change of F1 to UTP coupled with rotation was determined, and the results again were comparable to those for ATP, suggesting that F1 exerts torque upon the affinity change to UTP via rotation similar to ATP-driven rotation. Thus, the adenine-ring significantly enhances the binding rate, although it is not directly involved in force generation. Taking into account the findings from another study on F1 with mutated phosphate-binding residues, it was proposed that progressive bond formation between the phosphate region and catalytic residues is responsible for the rotation-coupled change in affinity.
authors.affiliation: Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan.
authors.forename: Hidenobu C
authors.initials: HC
authors.lastname: Arai
authors.affiliation: Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Yukawa
authors.affiliation: Laboratory of Chemical Biology and Molecular Imaging, School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Ryu John
authors.initials: RJ
authors.lastname: Iwatate
authors.affiliation: Laboratory of Chemical Biology and Molecular Imaging, School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Mako
authors.initials: M
authors.lastname: Kamiya
authors.affiliation: Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan; PRESTO, Japan Science and Technology Agency, Tokyo, Japan.
authors.forename: Rikiya
authors.initials: R
authors.lastname: Watanabe
authors.affiliation: Laboratory of Chemical Biology and Molecular Imaging, School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Yasuteru
authors.initials: Y
authors.lastname: Urano
authors.affiliation: Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan. Electronic address: hnoji@appchem.t.u-tokyo.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Noji
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism; D019415:Torque; D014544:Uridine Triphosphate / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases; D014544:Uridine Triphosphate