Nitrogenase reaction represents a major source of the usable form of nitrogen that supports the existence of human population. As such, understanding how small building blocks are assembled into a functional nitrogenase entity is of significant relevance to human health. Using combined genetic, biochemical, spectroscopic and structural approaches, we propose to investigate how M- and P-clusters of molybdenum nitrogenase are assembled via unique biochemical reactions into functional units. Specifically, we will investigate how two 4Fe modules are rearranged and coupled into an 8Fe core of M-cluster via radical SAM-dependent carbide insertion concomitant with the incorporation of a ?9th? sulfur, how two 4Fe modules are rearranged and coupled into an 8Fe P-cluster via unique redox reactions concomitant with the removal of an ?8th? sulfur, and how various assembly proteins interact with one another to facilitate the maturation of M- and P-clusters. Through our proposed studies, we expect to further refine the biosynthetic pathways of the unique metalloclusters of nitrogenase, which will provide crucial insights into the structural-functional relationship of this important enzyme and reveal some general principles of the assembly mechanisms of complex metalloclusters in biological systems.

Public Health Relevance

Using combined genetic, biochemical, spectroscopic and structural approaches, we propose to investigate how M- and P-clusters of molybdenum nitrogenase are assembled into functional units. Through our proposed studies, we expect to refine the biosynthetic mechanisms of these catalytically-important and chemically-unprecedented metalloclusters, which will provide crucial insights into the structural-functional relationship of nitrogenase and the general principles of the assembly of complex metalloclusters in biological systems.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM067626-15
Application #
9440426
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Anderson, Vernon
Project Start
2003-05-01
Project End
2020-11-30
Budget Start
2017-12-01
Budget End
2018-11-30
Support Year
15
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of California Irvine
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
046705849
City
Irvine
State
CA
Country
United States
Zip Code
92617
Rettberg, Lee A; Wilcoxen, Jarett; Lee, Chi Chung et al. (2018) Probing the coordination and function of Fe4S4 modules in nitrogenase assembly protein NifB. Nat Commun 9:2824
Tanifuji, Kazuki; Lee, Chi Chung; Sickerman, Nathaniel S et al. (2018) Tracing the 'ninth sulfur' of the nitrogenase cofactor via a semi-synthetic approach. Nat Chem 10:568-572
Rupnik, Kresimir; Lee, Chi Chung; Hu, Yilin et al. (2018) A VTVH MCD and EPR Spectroscopic Study of the Maturation of the ""Second"" Nitrogenase P-Cluster. Inorg Chem 57:4719-4725
Sickerman, Nathaniel S; Rettberg, Lee A; Lee, Chi Chung et al. (2017) Cluster assembly in nitrogenase. Essays Biochem 61:271-279
Fay, Aaron W; Blank, Michael A; Rebelein, Johannes G et al. (2016) Assembly scaffold NifEN: A structural and functional homolog of the nitrogenase catalytic component. Proc Natl Acad Sci U S A 113:9504-8
Hu, Yilin; Ribbe, Markus W (2016) Maturation of nitrogenase cofactor-the role of a class E radical SAM methyltransferase NifB. Curr Opin Chem Biol 31:188-94
Lee, Chi Chung; Sickerman, Nathaniel S; Hu, Yilin et al. (2016) YedY: A Mononuclear Molybdenum Enzyme with a Redox-Active Ligand? Chembiochem 17:453-5
Lee, Chi Chung; Fay, Aaron W; Weng, Tsu-Chien et al. (2015) Uncoupling binding of substrate CO from turnover by vanadium nitrogenase. Proc Natl Acad Sci U S A 112:13845-9
Wiig, Jared A; Hu, Yilin; Ribbe, Markus W (2015) Refining the pathway of carbide insertion into the nitrogenase M-cluster. Nat Commun 6:8034
Cahn, Jackson K B; Brinkmann-Chen, Sabine; Spatzal, Thomas et al. (2015) Cofactor specificity motifs and the induced fit mechanism in class I ketol-acid reductoisomerases. Biochem J 468:475-84

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