Light as a problem: biogenesis of photosynthetic complexes in cyanobacteria

Oxygenic photosynthesis performed by plant, algae and by cyanobacteria is a fundamental biochemical process essential for maintaining life on the Earth. The key component of photosynthetic apparatus is photosystem II (PSII), a sophisticated complex of proteins, pigments and cofactors, which is able to withdraw electrons from water. An enigmatic aspect of PSII is its biogenesis in the cell. It is certainly a delicate task since during formation of individual parts of this complex and their assembly, light acts as a destructive element. Scientists at the Laboratory of Photosynthesis (Institute of Microbiology, Třeboň) have recently elucidated molecular mechanisms underlying early stages of the PSII biogenesis. Using the cyanobacterium Synechocystis PCC 6803, a model organism frequently used for the study of photosynthetic apparatus, they showed a key role of small carotenoid-binding proteins in the process. These proteins are attached to PSII components during their biosynthesis and assembly and participate in delivery of pigments and dissipation of harmful light energy.