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H2 Regulation


Project Title:

Hydrogen regulation and global responses to electron, carbon, and nitrogen sources in Methanococcus maripaludis

PIs:

 John A. Leigh, University of Washington, leighj@u.washington.edu

William B. Whitman, University of Georgia

Murray Hackett, University of Washington

Nitin Baliga, Institute for Systems Biology

Funding: US Department of Energy Office of Basic Energy Sciences, Basic Research for the Hydrogen Fuel Initiative, Award No.DE-FG02-08ER64685

Project Goals:

1.  Use transcriptomics, proteomics, and metabolomics to study the systems biology of H2 metabolism, formate metabolism, nitrogen fixation, and carbon assimilation in Methanococcus maripaludis.

2.  Determine the mechanism of H2 sensing and transcriptional regulation by H2.

Background:

Methanogenic Archaea (methanogens) catalyze the critical, methane-producing step in the anaerobic decomposition of organic matter and have applications in carbon-neutral fuel production.  Most species of methanogens are hydrogenotrophic and use hydrogen gas (H2) as the electron donor for the reduction of carbon dioxide to methane.  In addition, many species can use formate in place of H2, and a few can use certain alcohols.  These microorganisms contain very high levels of different types of hydrogenases and consume H2 at very high rates.  In addition, under certain conditions the H2 uptake system can be induced to produce H2 at high rates; this occurs with formate as electron donor.  As another way to produce H2, certain species of methanogens fix nitrogen, and therefore have the potential to produce H2 using the nitrogenase system.  Finally, most hydrogenotrophic methanogens are autotrophs, and assimilate CO2 by the acetyl-CoA pathway.  Hence, the biology of hydrogenotrophic methanogens is relevant to potential bio-energy applications from the points of view of H2 production, nitrogen fixation, and carbon assimilation. We are engaged in a long-term effort to understand regulatory networks in hydrogenotrophic methanogens, members of the Archaea whose energy metabolism specializes in the use of H2 to reduce CO2 to methane. Our studies focus on Methanococcus maripaludis, a model species with good laboratory growth characteristics, facile genetic tools, and a tractable genome of 1722 annotated ORFs. A key aspect of our approach is the use of continuous culture for maintaining defined nutrient conditions (Haydock et al., 2004).

For more information, analysis and results see H2 Regulation pages.