The mobility of interfaces between monomers in dimeric bovine ATP synthase participates in the ultrastructure of inner mitochondrial membranes

Abstract

The angle between the central rotatory axes of the monomeric complexes varies between ca. 76o and ca. 95o . Some variations in this angle arise directly from the catalytic mechanism of the enzyme, and others are independent of catalysis. The monomer monomer interaction is mediated mainly by j-subunits attached to the surface of wedge shaped protein-lipid structures in the membrane domain of the complex, and the angular variation arises from rotational and translational changes in this interaction, and combinations of both. The structures also suggest how the dimeric ATP synthases might be interacting with each other to form the characteristic rows along the tips of the cristae via other inter-wedge contacts, moulding themselves to the range of oligomeric arrangements observed by tomography of mitochondrial membranes, and at the same time allowing the ATP synthase to operate under the range of physiological conditions that influence the structure of the cristae.