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

Edited by Peter Brzezinski

Received 7 February 2009; received in revised form 24 February 2009; accepted 26 February 2009. published online 03 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 Kd at 25°C. Here, we show that at [ATP]>2μM, ε does not affect rotation of PS3 F1-ATPase but, at 200nM 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 Kd.

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

a Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226-8503, Japan

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

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

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

PII: S0014-5793(09)00152-5

doi:10.1016/j.febslet.2009.02.038

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