Photosynthetic electron partitioning between [FeFe]-hydrogenase and ferredoxin:NADP+-oxidoreductase (FNR) enzymes in vitro

Photosynthetic water splitting, coupled to hydrogenase-catalyzed hydrogen production, is considered a promising clean, renewablesource of energy. It is widely accepted that the oxygen sensitivity of hydrogen production, combined with competition betweenhydrogenases and NADPH-dependent carbon dioxide fixation are the main limitations for its commercialization. Here we provideevidence that, under the anaerobic conditions that support hydrogen production, there is a significant loss of photosyntheticelectrons toward NADPH production in vitro. To elucidate the basis for competition, we bioengineered a ferredoxin-hydrogenasefusion and characterized hydrogen production kinetics in the presence of Fd, ferredoxin:NADP+-oxidoreductase (FNR), and NADP+. Replacing the hydrogenase with a ferredoxin-hydrogenase fusion switched the bias of electron transfer from FNR to hydrogenaseand resulted in an increased rate of hydrogen photoproduction. These results suggest a new direction for improvement of biohydrogenproduction and a means to further resolve the mechanisms that control partitioning of photosynthetic electron transport.

作 者：Yacoby, Iftach; Pochekailov, Sergii; Toporik, Hila; Ghirardi, Maria L.; King, Paul W.; Zhang, Shuguang
期刊名称： Proceedings of the National Academy of Sciences