PMID:11438702
| Citation |
Hutcheon, ML, Duncan, TM, Ngai, H and Cross, RL (2001) Energy-driven subunit rotation at the interface between subunit a and the c oligomer in the F(O) sector of Escherichia coli ATP synthase. Proc. Natl. Acad. Sci. U.S.A. 98:8519-24 |
|---|---|
| Abstract |
Subunit rotation within the F(1) catalytic sector of the ATP synthase has been well documented, identifying the synthase as the smallest known rotary motor. In the membrane-embedded F(O) sector, it is thought that proton transport occurs at a rotor/stator interface between the oligomeric ring of c subunits (rotor) and the single-copy a subunit (stator). Here we report evidence for an energy-dependent rotation at this interface. F(O)F(1) was expressed with a pair of substituted cysteines positioned to allow an intersubunit disulfide crosslink between subunit a and a c subunit [aN214C/cM65C; Jiang, W. & Fillingame, R. H. (1998) Proc. Natl. Acad. Sci. USA 95, 6607--6612]. Membranes were treated with N,N'-dicyclohexyl-[(14)C]carbodiimide to radiolabel the D61 residue on less than 20% of the c subunits. After oxidation to form an a--c crosslink, the c subunit properly aligned to crosslink to subunit a was found to contain very little (14)C label relative to other members of the c ring. However, exposure to MgATP before oxidation significantly increased the radiolabel in the a-c crosslink, indicating that a different c subunit was now aligned with subunit a. This increase was not induced by exposure to MgADP/P(i). Furthermore, preincubation with MgADP and azide to inhibit F(1) or with high concentrations of N,N'-dicyclohexylcarbodiimide to label most c subunits prevented the ATP effect. These results provide evidence for an energy-dependent rotation of the c ring relative to subunit a. |
| Links |
PubMed PMC37468 Online version:10.1073/pnas.151236798 |
| Keywords |
Adenosine Triphosphate/metabolism; Cross-Linking Reagents; Dicyclohexylcarbodiimide/metabolism; Energy Transfer; Enzyme Inhibitors/metabolism; Escherichia coli/enzymology; Protein Conformation; Proton-Translocating ATPases/antagonists & inhibitors; Proton-Translocating ATPases/chemistry; Proton-Translocating ATPases/metabolism |
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