title: Catalysis-enhancement via rotary fluctuation of F1-ATPase.
abstract: Protein conformational fluctuations modulate the catalytic powers of enzymes. The frequency of conformational fluctuations may modulate the catalytic rate at individual reaction steps. In this study, we modulated the rotary fluctuation frequency of F1-ATPase (F1) by attaching probes with different viscous drag coefficients at the rotary shaft of F1. Individual rotation pauses of F1 between rotary steps correspond to the waiting state of a certain elementary reaction step of ATP hydrolysis. This allows us to investigate the impact of the frequency modulation of the rotary fluctuation on the rate of the individual reaction steps by measuring the duration of rotation pauses. Although phosphate release was significantly decelerated, the ATP-binding and hydrolysis steps were less sensitive or insensitive to the viscous drag coefficient of the probe. Brownian dynamics simulation based on a model similar to the Sumi-Marcus theory reproduced the experimental results, providing a theoretical framework for the role of rotational fluctuation in F1 rate enhancement.
authors.affiliation: Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan.
authors.forename: Rikiya
authors.initials: R
authors.lastname: Watanabe
authors.forename: Kumiko
authors.initials: K
authors.lastname: Hayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueno
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Noji
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D055162:Biocatalysis; D001696:Biomechanical Phenomena; D017276:Friction; D006868:Hydrolysis; D007700:Kinetics; D008954:Models, Biological; D015335:Molecular Probes / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012399:Rotation; D014783:Viscosity
chemical_list: D015335:Molecular Probes; D010710:Phosphates; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases