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

AbstractThe structure of Escherichia coli F0F1-ATPase (ATP synthase), and its F0 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 ∼90 Å, and a height of ∼100 Å from the membrane surface. F0 sectors were visualized as two different ring-like structures (one with a central mass and the other with a central hollow of ≥ 18 Å depth) with a calculated outer diameter of ∼130 Å. 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 subunits in the F0 sector. Considering the stoichiometry of F0 subunits, the area of the image observed is large enough to accommodate all three F0 subunits in an asymmetric manner