Light-driven carbon dioxide reduction to methane by nitrogenase in a photosynthetic bacterium

Kathryn R. Fixena, Yanning Zhenga, Derek F. Harrisb, Sudipta Shawb, Zhi Yong Yangb, Dennis R. Deanc, Lance C. Seefeldtb, Caroline S. Harwooda

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Nitrogenase is an ATP-requiring enzyme capable of carrying out multielectron reductions of inert molecules. A purified remodeled nitrogenase containing two amino acid substitutions near the site of its FeMo cofactor was recently described as having the capacity to reduce carbon dioxide (CO2 ) to methane (CH4 ). Here, we developed the anoxygenic phototroph, Rhodopseudomonas palustris, as a biocatalyst capable of light-driven CO2 reduction to CH4 in vivo using this remodeled nitrogenase. Conversion of CO2 to CH4 by R. palustris required constitutive expression of nitrogenase, which was achieved by using a variant of the transcription factor NifA that is able to activate expression of nitrogenase under all growth conditions. Also, light was required for generation of ATP by cyclic photophosphorylation. CH4 production by R. palustris could be controlled by manipulating the distribution of electrons and energy available to nitrogenase. This work shows the feasibility of using microbes to generate hydrocarbons from CO2 in one enzymatic step using light energy.

Original languageEnglish (US)
Pages (from-to)10163-10167
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number36
DOIs
StatePublished - Sep 6 2016

Bibliographical note

Funding Information:
We thank the entire Biological and Electron Transfer and Catalysis (BETCy) team for helpful discussions. This work was supported as part of the BETCy Energy Frontier Research Center (EFRC), an EFRC funded by US Department of Energy, Office of Science Grant DE-SC0012518.

Keywords

  • Bioenergy
  • Engineered bacterium
  • Methane
  • Nitrogenase|Rhodopseudomonas

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