Functional proteomics and reverse genetics to elucidate hydrogen production in Chlamydomonas reinhardtii

Due to the rapid depletion of global oil supplies and the current environmental concerns regarding increased CO₂ levels and climate change, there is a considerable amount of interest in devising an efficient, economical, and zero CO₂ emission fuel to provide clean energy for the future. One promising energy source is hydrogen, which can be produced by photosynthetic organisms such as cyanobacteria and microalgae (Rupprecht et al., 2006). In addition to the potential large-scale production of hydrogen using microorganisms, hydrogen is an especially attractive renewable energy source because the combustion of hydrogen produces only H₂O as a byproduct.

An attractive candidate for hydrogen production is the green alga Chlamydomonas reinhardtii (Gaffron, 1939). Under specific conditions, C. reinhardtii can produce H₂ catalyzed by hydrogenase. Also, detailed studies of H₂ photoproduction have been done on C. reinhardtii and, compared to Cyanobacteria, C. reinhardtii has a more efficient hydrogen-producing enzyme (Kruse et al., 2005). A disadvantage of C. reinhardtii H₂ photoproduction is the extreme sensitivity of the hydrogenase to oxygen. However, by understanding the mechanism in hydrogen production, there is optimism that the pathway can be manipulated or engineered in such a way to overcome this limitation.

Our project will involve two approaches: (i) a discovery-driven approach, motivated by the necessity for further characterization of protein networks and (ii) a hypothesis-driven approach, based on the current understanding of the system. In the discovery-driven approach, we will combine comparative quantitative proteomics and molecular biology techniques to elucidate the key proteins involved in anaerobiosis and hydrogen production. The advantage of this approach is that, since it will be an unbiased survey of all the proteins involved, new knowledge of the system is guaranteed. In the hypothesis-driven approach, we will concentrate on the structure-function relationship of hydrogenase in the chloroplast.

References

Gaffron, H. (1939) Reduction of carbon dioxide with molecular hydrogen in green algae. Nature, 143, 240-205.

Kruse, O., Rupprecht, J., Mussgnug, J.H., Dismukes, G.C. and Hankamer, B. (2005) Photosynthesis: a blueprint for solar energy capture and biohydrogen production technologies. Photochem Photobiol Sci, 4, 957-970.

Rupprecht, J., Hankamer, B., Mussgnug, J.H., Ananyev, G., Dismukes, C. and Kruse, O. (2006) Perspectives and advances of biological H2 production in microorganisms. Appl Microbiol Biotechnol, 72, 442-449.