Structure and function of the cytochrome bc1 complex of mitochondria and photosynthetic bacteria

Progress has recently been made in the understanding of the function of the cytochrome bc(1) complex and related proteins in the context of recent structural information. The structures support many features that were predicted from sequence analysis and biophysical studies, but contain some surprises. Most dramatically, it is apparent that the iron-sulfur protein can take up different positions in different crystals, suggesting a novel mechanism for electron transfer through domain movement. Evidence from studies of mutant strains, in which the function of the sites or the binding of inhibitors is perturbed, has provided clues about the mechanism.