The γ subunit in chloroplast F 1 ‐ATPase can rotate in a unidirectional and counter‐clockwise manner

Rotation of the γ subunit in chloroplast F 1 ‐ATPase (CF 1 ) was investigated by using a single molecule observation technique, which is developed by Noji et al. to observe the rotation of a central γ subunit portion in the α 3 β 3 γ sub‐complex of F 1 ‐ATPase from thermophilic Bacillus PS3 (TF 1 ) during ATP hydrolysis [Noji, H. et al. (1997) Nature 386, 299–302]. We used two cysteines of the γ subunit (Cys‐199 and Cys‐205) of CF 1 ‐ATPase, which are involved in the regulation of this enzyme, to fix the fluorochrome‐labeled actin filament. Then we successfully observed a unidirectional, counter‐clockwise rotation of the actin filament with the fluorescent microscope indicating the rotation of the γ subunit in CF 1 ‐ATPase. We conclude that the rotation of the γ subunit in the F 1 ‐motor is a ubiquitous phenomenon in all F 1 ‐ATPases in prokaryotes as well as in eukaryotes.