Nitrogenase is a complex metalloenzyme that catalyzes one of the most remarkable chemical transformations in biological systems: the nucleotide-dependent reduction of atmospheric dinitrogen to bioavailable ammonia. There is an outstanding interest in decoding the assembly mechanism of nitrogenase, not only because of its significant relevance to nitrogenase-specific reactions, but also because of its tremendous implication for general metalloprotein biogenesis. Here we propose to greatly expand our understanding of the nitrogenase assembly process by combined genetic, biochemical, spectroscopic and structural approaches. The MoFe protein of the molybdenum nitrogenase of Azotobacter vinelandii will be the focus of the proposed investigation. Through our proposed studies, we expect to further refine the biosynthetic pathways of MoFe protein and its associated clusters, a continuous effort with an ultimate goal to unravel the molecular mechanism of nitrogenase assembly. Furthermore, using nitrogenase as a model system, we also hope to provide general themes of biological metal cluster assembly, which may, in the long run, prove instrumental in developing successful strategies for the chemical synthesis of complex metalloclusters. .

Public Health Relevance

Nitrogenase catalyzes the transformation of atmospheric dinitrogen to bioavailable ammonia, thereby supplying the reduced nitrogen, an essential component of nucleic acids and proteins, for the existence of human population. This particular proposal deals with the assembly of nitrogenase MoFe protein and its associated metalloclusters and the outcome of these studies will hopefully provide general themes of biological metal cluster assembly and facilitate future development of cost-efficient strategies for the chemical synthesis of catalytically active metalloclusters. As such, our proposed research may have additional economic value in addition to its intrinsic relevancy to human health.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Macromolecular Structure and Function A Study Section (MSFA)
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Anderson, Vernon
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University of California Irvine
Schools of Arts and Sciences
United States
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Hu, Yilin; Ribbe, Markus W (2015) Nitrogenase and homologs. J Biol Inorg Chem 20:435-45
Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W (2015) Catalytic reduction of CN-, CO, and CO2 by nitrogenase cofactors in lanthanide-driven reactions. Angew Chem Int Ed Engl 54:1219-22
Rebelein, Johannes G; Hu, Yilin; Ribbe, Markus W (2014) Differential reduction of CO? by molybdenum and vanadium nitrogenases. Angew Chem Int Ed Engl 53:11543-6
Hu, Yilin; Ribbe, Markus W (2014) A journey into the active center of nitrogenase. J Biol Inorg Chem 19:731-6
Ribbe, Markus W; Hu, Yilin; Hodgson, Keith O et al. (2014) Biosynthesis of nitrogenase metalloclusters. Chem Rev 114:4063-80
Rupnik, Kresimir; Lee, Chi Chung; Wiig, Jared A et al. (2014) Nonenzymatic synthesis of the P-cluster in the nitrogenase MoFe protein: evidence of the involvement of all-ferrous [Fe4S4](0) intermediates. Biochemistry 53:1108-16
Hu, Yilin; Ribbe, Markus W (2013) Biosynthesis of the iron-molybdenum cofactor of nitrogenase. J Biol Chem 288:13173-7
Lancaster, Kyle M; Hu, Yilin; Bergmann, Uwe et al. (2013) X-ray spectroscopic observation of an interstitial carbide in NifEN-bound FeMoco precursor. J Am Chem Soc 135:610-2
Wiig, Jared A; Lee, Chi Chung; Hu, Yilin et al. (2013) Tracing the interstitial carbide of the nitrogenase cofactor during substrate turnover. J Am Chem Soc 135:4982-3
Hu, Yilin; Ribbe, Markus W (2013) Nitrogenase assembly. Biochim Biophys Acta 1827:1112-22

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