Observations of rotation within the FoF1‐ATP synthase: deciding between rotation of the Foc subunit ring and artifact
Open Access
- 27 March 2000
- journal article
- Published by Wiley in FEBS Letters
- Vol. 470 (3) , 244-248
- https://doi.org/10.1016/s0014-5793(00)01336-3
Abstract
FoF1‐ATP synthase mediates coupling of proton flow in Fo and ATP synthesis/hydrolysis in F1 through rotation of central rotor subunits. A ring structure of Fo c subunits is widely believed to be a part of the rotor. Using an attached actin filament as a probe, we have observed the rotation of the Fo c subunit ring in detergent‐solubilized FoF1‐ATP synthase purified from Escherichia coli. Similar studies have been performed and reported recently [Sambongi et al. (1999) Science 286, 1722–1724]. However, in our hands this rotation has been observed only for the preparations which show poor sensitivity to dicyclohexylcarbodiimde, an Fo inhibitor. We have found that detergents which adequately disperse the enzyme for the rotation assay also tend to transform FoF1‐ATP synthase into an Fo inhibitor‐insensitive state in which F1 can hydrolyze ATP regardless of the state of the Fo. Our results raise the important issue of whether rotation of the Fo c ring in isolated FoF1‐ATP synthase can be demonstrated unequivocally with the approach adopted here and also used by Sambongi et al.Keywords
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