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 simi lar to 90 Angstrom, and a height of similar to 100 Angstrom from the m embrane surface. F-o sectors were visualized as two different ring-lik e structures (one with a central mass and the other with a central hol low of greater than or equal to 18 Angstrom depth) with a calculated o uter diameter of similar to 130 Angstrom. The two different images pos sibly represent the opposite orientations of the complex in the membra nes. The ring-like projections of both images suggest inherently asymm etric assemblies of the submits in the F-0 sector, Considering the sto ichiometry of F-0 submits, the area of the image observed is large eno ugh to accommodate all three F-0 subunits in an asymmetric manner.