Rotary torque produced by proton motive force in FoF1 motor

We have attempted direct observation of the light-driven rotation of a FoF1-ATP motor. The FoF1-ATP motor was co-reconstituted by the deletion-δ subunit of FoF1-ATP synthase with bacteriorhodopsins (BRs) into a liposome. The BR converts radiation energy into electrochemical gradient of proton to drive the FoF1-ATP motor. Therefore, the light-driven rotation of FoF1-ATP motor has been directly observed by a fluorescence microscopy using a fluorescent actin filament connected to β-subunit as a marker of its orientation. The rotational torque value of the Fo motor was calculated as 27.93 ± 1.88 pN nm. The ATP motor is expected to be a promising rotary molecular motor in the development of nanodevices.