ATP-driven stepwise rotation of FoF1-ATP synthase

Hiroshi Ueno, Toshiharu Suzuki, Kazuhiko Kinosita, Masasuke Yoshida

研究成果: Article査読

122 被引用数 (Scopus)


FoF1-ATP synthase (FoF1) is a motor enzyme that couples ATP synthesis/hydrolysis with a transmembrane proton translocation. F1, a water-soluble ATPase portion of F oF1, rotates by repeating ATP-waiting dwell, 80° substep rotation, catalytic dwell, and 40°-substep rotation. Compared with F1, rotation of FoF1 has yet been poorly understood, and, here, we analyzed ATP-driven rotations of FoF 1. Rotation was probed with an 80-nm bead attached to the ring of c subunits in the immobilized FoF1 and recorded with a submillisecond fast camera. The rotation rates at various ATP concentrations obeyed the curve defined by a Km of ≈30 μM and a V max of ≈350 revolutions per second (at 37°C). At low ATP, ATP-waiting dwell was seen and the kon-ATP was estimated to be 3.6 × 107 M-1·s-1. At high ATP, fast, poorly defined stepwise motions were observed that probably reflect the catalytic dwells. When a slowly hydrolyzable substrate, adenosine 5′-[γ-thio]triphosphate, was used, the catalytic dwells consisting of two events were seen more clearly at the angular position of ≈80°. The rotational behavior of FoF1 resembles that of F 1. This finding indicates that "friction" in Fo motor is negligible during the ATP-driven rotation. Tributyltin chloride, a specific inhibitor of proton translocation, slowed the rotation rate by 96%. However, dwells at clearly defined angular positions were not observed under these conditions, indicating that inhibition by tributyltin chloride is complex.

ジャーナルProceedings of the National Academy of Sciences of the United States of America
出版ステータスPublished - 2005 2 1

ASJC Scopus subject areas

  • Genetics
  • General

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