Understanding nitrogenase maturation and activity in methanogens

Daniel J. Lessner, University of Arkansas (Principal Investigator)

Eduardus C. Duin, Auburn University (Co-Investigator)

The overall goal of the continued research project is to elucidate and characterize the factors that control the maturation and activity of nitrogenase in methanogenic archaea (methanogens). Nitrogenase is a metalloenzyme system found only in bacteria and archaea where it functions in biological nitrogen fixation by reducing dinitrogen to ammonia. Nitrogenase is important for bioenergy research since it also directly catalyzes the production of biofuels (e.g., H₂), it serves as a model to understand complex metallocofactor biogenesis, and functional production in plants would alleviate the burden to synthesize fertilizers from fossil fuels. Previous results indicate that the assembly, activity, and regulation of nitrogenase in methanogens is distinct from bacteria, which may provide alternative avenues to optimize and/or develop metalloenzyme-based energy production strategies. The long-term goals of this research project are to use genetically tractable Methanosarcina acetivorans as a model to 1) determine the regulation and catalytic abilities of methanogen nitrogenases, 2) determine the factors involved in cofactor assembly and maturation in methanogen nitrogenases, and 3) determine how electron transfer to nitrogenase is integrated with methanogenesis. Results generated are expected to significantly expand the understanding of the factors that control nitrogenase maturation and activity in methanogens that may lead to improved and/or new methods to produce nitrogenase and other metalloenzymes in native and/or heterologous hosts (e.g., plants) and the ability to engineer and optimize new energy-relevant pathways in methanogens and other archaea.