ABSTRACT
As part of the mitochondrial respiratory chain and the photosynthetic apparatus of nonoxygenic purple bacteria, the cytochrome bc 1 complex couples the oxidation of quinol to proton translocation across the membrane, contributing to the proton motive force essential for a variety of cellular activities such as ATP synthesis. With the accumulation of information from biochemical, genetic, and structural investigations, an understanding of the mechanism by which the complex performs its biological function and the way it is inhibited has been obtained at an unprecedented level of detail. With their unique genetic background, photosynthetic bacteria afford an indispensible and convenient system that has been used 328extensively in functional and structural studies of the cytochrome bc 1 complex. In this chapter, we review contributions from many laboratories including our own and point out certain challenges that lie ahead.
