Photosynthetic Electron Partitioning Between [FeFe] Hydrogenase and Ferredoxin: NADP+-Oxidoreductase (FNR) Enzymes in Vitro

Iftach Yacoby, Sergii Pochekailov, Hila Toporik, Maria L. Ghirardi, Paul W. King, Shuguang Zhang

Research output: Contribution to journalArticlepeer-review

157 Scopus Citations


Photosynthetic water splitting, coupled to hydrogenase-catalyzed hydrogen production, is considered a promising clean, renewable source of energy. It is widely accepted that the oxygen sensitivity of hydrogen production, combined with competition between hydrogenases and NADPH-dependent carbon dioxide fixation are the main limitations for its commercialization. Here we provide evidence that, under the anaerobic conditions that support hydrogen production, there is a significant loss of photosynthetic electrons toward NADPH production in vitro. To elucidate the basis for competition, we bioengineered a ferredoxin-hydrogenase fusion 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 hydrogenase and resulted in an increased rate of hydrogen photoproduction. These results suggest a new direction for improvement of biohydrogen production and a means to further resolve the mechanisms that control partitioning of photosynthetic electron transport.

Original languageAmerican English
Pages (from-to)9396-9401
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number23
StatePublished - 2011

NREL Publication Number

  • NREL/JA-2700-51092


  • photosystems
  • protein engineering
  • water-splitting enzyme


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