The γ subunit in chloroplast F1‐ATPase can rotate in a unidirectional and counter‐clockwise manner

摘要

>Rotation of the γ subunit in chloroplast F₁-ATPase (CF₁) 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 α₃β₃γ sub-complex of F₁-ATPase from thermophilic Bacillus PS3 (TF₁) 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 CF₁-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 CF₁-ATPase. We conclude that the rotation of the γ subunit in the F₁-motor is a ubiquitous phenomenon in all F₁-ATPases in prokaryotes as well as in eukaryotes.