Subunit rotation in F0F1-ATP synthases as a means of coupling proton transport through F0 to the binding changes in F1.

The rotation of an asymmetric core of subunits in F0F1-ATP synthases has been proposed as a means of coupling the exergonic transport of protons through F0 to the endergonic conformational changes in F1 required for substrate binding and produce release. Here we review earlier evidence both for and against subunit rotation and then discuss our most recent studies using reversible intersubunit disulfide cross-links to test for rotation. We conclude that the gamma subunit of F1 rotates relative to the surrounding catalytic subunits during catalytic turnover by both soluble F1 and membrane-bound F0F1. Furthermore, the inhibition of this rotation by the modification of F0 with DCCD suggests that rotation in F1 is obligatorily coupled to rotation in F0 as an integral part of the coupling mechanism.