FEBE Letters
Volume 583, Issue 7, 2 April 2009, Pages 1121-1126

doi:10.1016/j.febslet.2009.02.038    

Copyright © 2009 Federation of European Biochemical Societies Published by Elsevier B.V.

Effect of ε subunit on the rotation of thermophilic Bacillus F₁-ATPase

Masato Tsumuraya^a, Shou Furuike^b, Kengo Adachi^b, Kazuhiko Kinosita Jr.^b and Masasuke Yoshida^{a, c,} *

^aChemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226-8503, Japan

^bDepartment of Physics, Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 169-8555, Japan

^cICORP ATP Synthesis Regulation Project, Japan Science and Technology Corporation (JST), Aomi 2-41, Tokyo 135-0064, Japan

Received 7 February 2009;
revised 24 February 2009;
accepted 26 February 2009.
Available online 3 March 2009.

Abstract

F₁-ATPase is an ATP-driven motor in which γε rotates in the α₃β₃-cylinder. It is attenuated by MgADP inhibition and by the ε subunit in an inhibitory form. The non-inhibitory form of ε subunit of thermophilic Bacillus PS3 F₁-ATPase is stabilized by ATP-binding with micromolar K_d at 25 °C. Here, we show that at [ATP] > 2 μM, ε does not affect rotation of PS3 F₁-ATPase but, at 200 nM ATP, ε prolongs the pause of rotation caused by MgADP inhibition while the frequency of the pause is unchanged. It appears that ε undergoes reversible transition to the inhibitory form at [ATP] below K_d.

Keywords: F₁; F₁-ATPase; ATP synthase; Motor; Single-molecule; Epsilon subunit


*Corresponding author. Address: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226-8503, Japan. Fax: +81 45 924 5277.