Abstract
The cytochrome b6f complex mediates electron transfer between Photosystem II and Photosystem I. The electron transfer events are linked to proton translocation across the membrane. Three-dimensional structures of the b6f complex with the quinone analogue inhibitor, TDS, have been reported at 3.0 A and 3.1 A resolutions, respectively, from M. laminosus and C. reinhardti. Structures of the native complex, and complex co-crystallized the quinone analogue DBMIB, have also been obtained from M. laminosus at a resolution of 3.4 A and 3.8 A. These structural details have provided deeper insight into the pathways and mechanisms that govern electron and proton traffic across the membrane. Three novel prosthetic groups, a chlorophyll a, a β-carotene, and a structurally unique heme, are present in the b6f complex that are not found in the related bc1 complex. It is hypothesized that these unique prosthetic groups can function alternatively, such as in the cyclic electron transport.
