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

Proc Natl Acad Sci U S A. 2011 Jun 7;108(23):9396-401. doi: 10.1073/pnas.1103659108. Epub 2011 May 23.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Algorithms
  • Amino Acid Sequence
  • Chlamydomonas reinhardtii / enzymology
  • Chlamydomonas reinhardtii / metabolism
  • Electron Transport / physiology
  • Ferredoxin-NADP Reductase / genetics
  • Ferredoxin-NADP Reductase / metabolism*
  • Ferredoxins / genetics
  • Ferredoxins / metabolism
  • Hydrogen / metabolism
  • Hydrogenase / genetics
  • Hydrogenase / metabolism*
  • Iron-Sulfur Proteins / genetics
  • Iron-Sulfur Proteins / metabolism*
  • Kinetics
  • Light
  • Models, Biological
  • NADP / metabolism
  • Photosynthesis / physiology
  • Photosystem I Protein Complex / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Protein Binding
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Thylakoids / enzymology*
  • Thylakoids / metabolism
  • Thylakoids / radiation effects


  • Ferredoxins
  • Iron-Sulfur Proteins
  • Photosystem I Protein Complex
  • Plant Proteins
  • Recombinant Fusion Proteins
  • NADP
  • Hydrogen
  • iron hydrogenase
  • Hydrogenase
  • Ferredoxin-NADP Reductase