In Vivo Assembly of Photosystem I-Hydrogenase Chimera for In Vitro PhotoH_2 Production

摘要

Photosynthetic hydrogen (photoH_2) production is an elegant approach tostoring solar energy. The most efficient strategy is to couple the hydrogenproducingenzyme, the hydrogenase (H_2ase), directly to photosystem I (PSI),which is a light-driven nanomachine found in photosynthetic organisms.PSI–H_2ase fusions have been tested in vivo and in vitro. Both approacheshave each their specific advantages and drawbacks. Here, a system to combineboth approaches by assembling PSI–H_2ase fusions in vivo for in vitrophotoH_2 production is established. For this, cyanobacterial PSI–H_2ase fusionmutants are generated and characterized concerning photoH_2 production invivo. The chimeric protein is purified and embedded in a redox polymer onan electrode where it successfully produces photoH_2 in vitro. The combinationof in vivo and in vitro processes comes along with reciprocal benefits.The in vivo assembly ensures that the chimeric protein is fully functionaland suited for the fabrication of bioelectrodes in vitro. At the same time, thephotoelectrochemicalin vitro characterization now permits to analyze theassemblies in detail. This will open avenues to optimize in vivo and in vitroapproaches for photoH_2 production in a target-oriented manner in the future.