title: Inhibition of thermophilic F1-ATPase by the ε subunit takes different path from the ADP-Mg inhibition.
abstract: The F1-ATPase, the soluble part of FoF1-ATP synthase, is a rotary molecular motor consisting of α3β3γδε. The γ and ε subunits rotate relative to the α3β3δ sub-complex on ATP hydrolysis by the β subunit. The ε subunit is known as an endogenous inhibitor of the ATPase activity of the F1-ATPase and is believed to function as a regulator of the ATP synthase. This inhibition by the ε subunit (ε inhibition) of F1-ATPase from thermophilicBacillusPS3 was analyzed by single molecule measurements. By using a mutant ε subunit deficient in ATP binding, reversible transitions between active and inactive states were observed. Analysis of pause and rotation durations showed that the ε inhibition takes a different path from the ADP-Mg inhibition. Furthermore, the addition of the mutant ε subunit to the α3β3γ sub-complex was found to facilitate recovery of the ATPase activity from the ADP-Mg inhibition. Thus, it was concluded that these two inhibitions are essentially exclusive of each other.
authors.affiliation: Department of Life Science, Rikkyo University, 3-34-1, Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan; Frontier Project "Adaptation and Evolution of Extremophile", College of Science, Rikkyo University, 3-34-1, Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Haruyama
authors.affiliation: Institute of Industrial Science, the University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hirono-Hara
authors.affiliation: Department of Life Science, Rikkyo University, 3-34-1, Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan; Frontier Project "Adaptation and Evolution of Extremophile", College of Science, Rikkyo University, 3-34-1, Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kato-Yamada
keywords: ADP inhibited form; ATP synthase; regulation