The F₀ Complex of the Escherichia Coli ATP Synthase

Abstract

Cholate-solubilized F, complexes of the ATP synthase (F,F,) from Escherichia coli were studied by application of conventional transmission electron microscopy and electron spectroscopic imaging (ESI) of negatively stained samples. Using the ESI mode, the structural organization of the F, complex (diameter of 7.5 5 0.5 nm) could be observed in more detail and defined projections could be distinguished. Projection A appears as a deltoid-like structure with bilateral symmetry. Projection B has an overall trapezoidal shape with some similarity in shape to the letter W. Applying the ESI mode to the uc complex dissolved in cholate-containing buffer, an elongated structure consisting of two intensity maxima could be observed. Simulations with models of the F, and the ac complex revealed that the projections observed can be obtained by tilting and rotating a model in which subunit a and the two copies of subunit b are located outside the subunit c oligomer. This view of structural organization was supported by results obtained with F, complexes decorated with monoclonal antibodies against subunits a, b or c.

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

“…1D) revealed that, in b~th types of rings, one half of the ring was about twice as thick as the other half (Table 1), although both halves (ridges) of the ring-like structures exhibited similar heights ( < 10 A). S~lch asymmetry of the F0 sector was also found in a recent electron microscopic study [17]. It is noteworthy that, regardle~s of the presence of a central mass, a similar ring structure ~as observed in this study ( Table 1).…”

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“…A last remark about V-type ATPase concerns the height of V 0 over the membrane, which is 80-85 A, (Figures 2I, J and strings), which indicates that in several features the V-type is somewhat larger than the F-type enzyme, where the height is 65 A and the c-oligomer has a diameter of 62 A (Boekema et al 1988b). If the membrane-anchored stator part is as wide as in V 0 (25 A) and the stator is arranged in a similar way as in V-type ATPase, this would imply that the a-type subunit is arranged between b and c, in contrast to other EM data (Birkenhäger et al 1995), but in agreement with recent models (Engelbrecht and Junge 1997).…”

Subunit Interactions in the Clathrin-coated Vesicle Vacuolar (H+)-ATPase Complex

“…F 1 appears to be attached to the F 0 domain via both a central stalk (believed to include both the ␥ and ⑀ subunits) and a peripheral stalk (composed of the ␦ subunit and the soluble portions of subunit b) (20, 21). The F 0 domain contains a ring of c subunits with the a and b subunits to one side (12,23).While the V-ATPase complex is thought to resemble the F-ATPases, electron micrographs have revealed significant differences (24, 25), and very little is known concerning the arrangement of subunits in the V-ATPase complex. In the current study, we have employed covalent cross-linking and Western blot analysis to identify subunit contacts within the V-ATPase.…”

“…F 1 appears to be attached to the F 0 domain via both a central stalk (believed to include both the ␥ and ⑀ subunits) and a peripheral stalk (composed of the ␦ subunit and the soluble portions of subunit b) (20, 21). The F 0 domain contains a ring of c subunits with the a and b subunits to one side (12,23).…”