Chloroplast F 0 F 1 ATP Synthase Imaged by Atomic Force Microscopy

Author： Neff D. Tripathi S. Middendorf K. Stahlberg H. Butt H.J. Bamberg E. dencher N.A.

ISSN： 1047-8477

Source： Journal of Structural Biology, Vol.119, Iss.2, 1997-07, pp. : 139-148

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Abstract

The F 0 F 1 ATP synthase of chloroplasts was imaged using atomic force microscopy (AFM) in contact mode under physiological conditions. Chloroplast (CF 0 F 1 ) ATP synthases were reconstituted into liposomes. Liposomes were adsorbed on a mica surface where they spread and formed lipid bilayers containing CF 0 F 1 ATP synthases which could be imaged. From these reconstituted CF 0 F 1 ATP synthases, the CF 1 part could be removed either by application of a chemical denaturant or less efficiently by mechanical stripping with the AFM tip. Embedded in the lipid bilayer were seen ring-like structures with a central dimple with outer diameters of 20 ± 3 nm (chemical denaturant) and ca. 7 nm (mechanical stripping), respectively. Ring-like structures were also observed in a protein-free lipid bilayer. These had diameters of 30 ± 5 nm and could be clearly distinguished from the structures observed after mechanical stripping. Hence, the ring-like structures observed after mechanical stripping might represent the intrinsic membrane domain CF 0 or the oligomer of its subunit III. In addition, isolated CF 1 adsorbed directly onto the mica surface was imaged. In accordance with the size known from electron microscopy, a diameter of 13 ± 4 nm was measured.