SUBUNIT ROTATION IN F0F1-ATP SYNTHASES AS A MEANS OF COUPLING PROTON TRANSPORT THROUGH F-0 TO THE BINDING CHANGES IN F1

The rotation of an asymmetric core of subunits in F0F1-ATP synthases h as been proposed as a means of coupling the exergonic transport of pro tons through F-0 to the endergonic conformational changes in F-1 requi red for substrate binding and product release. Here we review earlier evidence both for and against subunit rotation and then discuss our mo st recent studies using reversible intersubunit disulfide cross-links to test for rotation. We conclude that the gamma subunit of F-1 rotate s relative to the surrounding catalytic subunits during catalytic turn over by both soluble F-1 and membrane-bound F0F1. Furthermore, the inh ibition of this rotation by the modification of F-0 with DCCD suggests that rotation in F-1 is obligatorily coupled to rotation in F-0 as an integral part of the coupling mechanism.