title: Chemomechanical coupling in F1-ATPase revealed by simultaneous observation of nucleotide kinetics and rotation.
abstract: F(1)-ATPase is a rotary molecular motor in which unidirectional rotation of the central gamma subunit is powered by ATP hydrolysis in three catalytic sites arranged 120 degrees apart around gamma. To study how hydrolysis reactions produce mechanical rotation, we observed rotation under an optical microscope to see which of the three sites bound and released a fluorescent ATP analog. Assuming that the analog mimics authentic ATP, the following scheme emerges: (i) in the ATP-waiting state, one site, dictated by the orientation of gamma, is empty, whereas the other two bind a nucleotide; (ii) ATP binding to the empty site drives an approximately 80 degrees rotation of gamma; (iii) this triggers a reaction(s), hydrolysis and/or phosphate release, but not ADP release in the site that bound ATP one step earlier; (iv) completion of this reaction induces further approximately 40 degrees rotation.
authors.affiliation: Kansai Advanced Research Center, Protein Biophysics Group, Iwaoka 588-2, Nishi-ku, Kobe 651-2492, Japan. takayuki.nishizaka@gakushuin.ac.jp
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nishizaka
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Oiwa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Noji
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kimura
authors.forename: Eiro
authors.initials: E
authors.lastname: Muneyuki
authors.forename: Masasuke
authors.initials: M
authors.lastname: Yoshida
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kinosita
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology; D006868:Hydrolysis; D007700:Kinetics; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases