Matthew C. Posewitz - Research Scientist

phone: 303-384-6350
email: Matthew.Posewitz@nrel.gov
At NREL since 2002

Dr. Matthew Posewitz is a Research Professor at the Colorado School of Mines and a visiting Research Scientist at NREL. His research is focused on the study of photosynthetic organisms capable of producing H₂. His current research is aimed at identifying genes that influence H₂ photoproduction in the green alga Chlamydomonas reinhardtii. Recently, these studies resulted in the discovery of the [FeFe]-hydrogenase assembly genes, which are essential for the formation of an active [FeFe]-hydrogenase and are conserved among organisms containing [FeFe]-hydrogenase enzymes (see Posewitz et al., J. Biol. Chem. 279, 25711–25720, 2004). These studies have subsequently led to the ability to heterologously express these unique enzymes, which are among the most efficient H₂-generating catalysts known. This advance will accelerate the ability of scientists to generate and test recombinant enzymes for improved functionality and to further characterize [FeFe]-hydrogenase enzymes. Moreover, this research identified a C. reinhardtii mutant that is unable to accumulate intracellular starch and found that hydrogenase transcription and hydrogen production are attenuated in this mutant. This research established the importance of starch accumulation to H₂ production in this alga (see Posewitz et al., Plant Cell 16, 2151–2163, 2004).

Additional research projects include: 1) Changes in cellular gene transcription in wild-type and mutant cultures of C. reinhardtii adapted to conditions that promote H₂ production (in collaboration with Arthur Grossman’s laboratory at Stanford University), 2) Screening collections of microalgae for robust organisms capable of efficient H₂ photoproduction (in collaboration with Charles Dismukes, and Ed Steifel, Princeton University; Robert Bidigare, University of Hawaii; Eric Hegg, University of Utah; and Donald Bryant, Pennsylvania State University), 3) Development of gene shuffling techniques to increase the diversity of [FeFe]-hydrogenases.

Education

Selected Publications

1. Posewitz, M.C., King, P.W., Smolinksi, S.L., Smith, R.D., Ginley, A.R., Ghirardi, M.L., Seibert, M., “Identification of genes required for hydrogenase activity in Chlamydomonas reinhardtii,” Biochemical Society Transactions 33, 102–104 (2005).
2. Ghirardi, M.L., King, P.W., Posewitz, M.C., Maness, P.-C., Fedorov, A., Kim, K., Cohen, J., Schulten, K., Seibert, M., “Approaches to developing biological H₂-photoproducing organisms and processes,” Biochemical Society Transactions 33, 70–72 (2005).
3. Cohen, J., Kim, K., Posewitz, M., Ghirardi, M.L., Schulten, K., Seibert, M., King, P., “Molecular dynamics and experimental investigation of H₂ and O₂ diffusion in [Fe]-hydrogenase,” Biochemical Society Transactions 33, 80–82 (2005).
4. Posewitz, M.C., Smolinski, S.L., Melis, A., Kanakagiri, S., Seibert, M., Ghirardi, M.L., “Disruption of an isoamylase gene in Chlamydomonas reinhardtii attenuates hydrogen production and starch accumulation, Plant Cell 16, 2151–2163 (2004).
5. Posewitz, M.C., King, P., Smolinski, S.L., Zhang, L., Seibert, M., Ghirardi, M.L., “Discovery of two novel radical S-adenosylmethionine proteins required for the assembly of an active [Fe]-hydrogenase,” Journal of Biological Chemistry 279, 25711–25720 (2004).
6. Forestier, M., King P., Zhang, L., Posewitz, M., Schwarzer S., Happe, T., Ghirardi, M.L., Seibert M., “Expression of two [Fe]-hydrogenases in Chlamydomonas reinhardtii under anaerobic conditions,” European Journal of Biochemistry 270, 2750–2758 (2003).

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