Photoaffinity cross-linking of the coupling factor 1 from Micrococcus luteus by 3'-arylazido-8-azido-ATP.

The vicinity of nucleotide binding sites and the mechanism of ATP synthesis/hydrolysis have been studied with the bifunctional photosensitive ATP analog 3'-arylazido-8-azido-ATP. 3'-Arylazido-8-azido-ATP is hydrolyzed by the F1-ATPase from Micrococcus luteus in the absence of ultraviolet light. Irradiation, by ultraviolet light, of F1-ATPase in the presence of 3'-arylazido-8-azido-ATP results in the specific formation of cross-links between alpha and beta subunits. The results suggest that a hydrolytic nucleotide binding site is located on a beta subunit at or near an alpha subunit, probably at the interface between these subunits. Such a constellation would permit direct subunit-subunit interactions during ATP synthesis/hydrolysis.