Molecular imaging of Escherichia coli F0F1-ATPase in reconstituted membranes using atomic force microscopy

The structure of Escherichia coli F0F1-ATPase (ATP synthase), and its F-0 sector reconstituted in lipid membranes was analyzed using atomic force microscopy (AFM) by tapping-mode operation, The majority of F0F1-ATPases were visualized as spheres with a calculated diameter of similar to 90 Angstrom, and a height of similar to 100 Angstrom from the membrane surface. F-o sectors were visualized as two different ring-like structures (one with a central mass and the other with a central hollow of greater than or equal to 18 Angstrom depth) with a calculated outer diameter of similar to 130 Angstrom. The two different images possibly represent the opposite orientations of the complex in the membranes. The ring-like projections of both images suggest inherently asymmetric assemblies of the submits in the F-0 sector, Considering the stoichiometry of F-0 submits, the area of the image observed is large enough to accommodate all three F-0 subunits in an asymmetric manner.