Structural changes in the gamma and epsilon subunits of the Escherichia coli F1F0-type ATPase during energy coupling.

Structural changes in the Escherichia coli ATP synthase (ECF1F0) occur as part of catalysis, cooperativity and energy coupling within the complex. The gamma and epsilon subunits, two major components of the stalk that links the F1 and F0 parts, are intimately involved in conformational coupling that links catalytic site events in the F1 part with proton pumping through the membrane embedded F0 section. Movements of the gamma subunit have been observed by electron microscopy, and by cross-linking and fluorescence studies in which reagents are bound to Cys residues introduced at selected sites by mutagenesis. Conformational changes and shifts of the epsilon subunit related to changes in nucleotide occupancy sites have been followed by similar approaches.