Nanodissection of protein-protein interactions in energy transducing membrane protein complexes

The major energy transducing reactions in the biosphere are mediated by membrane protein complexes that convert and store solar energy as a protonmotive force (photosynthesis), or sequentially transfer electrons to oxygen (respiration). Each of these globally important processes requires that a membrane-extrinsic electron carrier docks onto a large, membrane -bound complex, as for example with cytochrome c and cytochrome aa3 oxidase in mitochondria. Although the structures of all of the photosynthetic or respiratory components are known, little is known of the intermolecular forces involved in establishing transient electron transfer complexes at the membrane surface. Moreover, the protein-protein and protein-cofactor interactions that stabilize these multisubunit complexes are also unknown.