The Molecular Role of the PufX Protein in Bacterial Photosynthetic Electron Transfer

The occurrence of photosynthetic activity in bacteria offers an excellent opportunity for studying the primary events of photosynthesis at the molecular level, due to the greater simplicity of these organisms with respect to eukaryots. In both classes of organisms the light reactions of photosynthesis are carried out by a series of multiproteic complexes embedded in specialized membranes. The general strategy for transducing light energy into a chemical potential consists in a sequence of electron transfer reactions: shuttling of electrons involving different membrane complexes results in an electrochemical potential difference for protons across the photosynthetic membrane. This electrochemical gradient is used primarily by the ATP-synthase to produce ATP from ADP and Pi, thus satisfying the metabolic energy request of the bacteria.