Redox Regulation of the Rotation of F1-ATP Synthase

In F1-ATPase, the smallest known motor enzyme, unidirectional rotation of the central axis subunit γ is coupled to ATP hydrolysis. In the present study, we report the redox switching of the rotation of this enzyme. For this purpose, the switch region from the γ subunit of the redox-sensitive chloroplast F1-ATPase was introduced into the bacterial F1-ATPase. The ATPase activity of the obtained complex was increased up to 3-fold upon reduction (Bald, D., Noji, H., Stumpp, M. T., Yoshida, M. & Hisabori, T. (2000) J. Biol. Chem. 275, 12757–12762). Here, we successfully observed the modulation of rotation of γ in this chimeric complex by changes in the redox conditions. In addition we revealed that the suppressed enzymatic activity of the oxidized F1-ATPase complex was characterized by more frequent long pauses in the rotation of the γ subunit. These findings obtained by the single molecule analysis therefore provide new insights into the mechanisms of enzyme regulation.