Structural evidence for a dynamic metallocofactor during N<sub>2</sub> reduction by Mo-nitrogenase

doi:10.1126/science.aaz6748

GSTDTAP > 气候变化

DOI	10.1126/science.aaz6748
	Structural evidence for a dynamic metallocofactor during N₂ reduction by Mo-nitrogenase
	Wonchull Kang; Chi Chung Lee; Andrew J. Jasniewski; Markus W. Ribbe; Yilin Hu
	2020-06-19
发表期刊	Science
出版年	2020
英文摘要	The enzyme nitrogenase uses adenosine triphosphate and several unusual iron-sulfur cofactors to pump electrons into typically inert dinitrogen (N2), providing protons along the way. Previous work has shown that sulfur atoms in the iron-molybdenum cofactor (FeMoCo) are labile and suggests that replacement of one of the sulfurs by N2 is integral to the mechanism of N2 binding and reduction. Through the elimination of excess reducing agent during preparation, Kang et al. determined structures of Mo-nitrogenase in a resting conformation. Unexpectedly, they found that all three sulfurs at the outer edge of FeMoCo appear to be labile, with one subunit even having two of three sulfurs replaced by light, diatomic ligands. Biochemical and spectroscopic data indicate that the protein is active, holds tightly bound N2, and is in the expected oxidation state. These results may prompt a reassessment of the possible mechanisms of N2 reduction and the role of dynamic belt ligands in FeMoCo. Science , this issue p. [1381][1] The enzyme nitrogenase uses a suite of complex metallocofactors to reduce dinitrogen (N2) to ammonia. Mechanistic details of this reaction remain sparse. We report a 1.83-angstrom crystal structure of the nitrogenase molybdenum-iron (MoFe) protein captured under physiological N2 turnover conditions. This structure reveals asymmetric displacements of the cofactor belt sulfurs (S2B or S3A and S5A) with distinct dinitrogen species in the two αβ dimers of the protein. The sulfur-displaced sites are distinct in the ability of protein ligands to donate protons to the bound dinitrogen species, as well as the elongation of either the Mo–O5 (carboxyl) or Mo–O7 (hydroxyl) distance that switches the Mo-homocitrate ligation from bidentate to monodentate. These results highlight the dynamic nature of the cofactor during catalysis and provide evidence for participation of all belt-sulfur sites in this process. [1]: /lookup/doi/10.1126/science.aaz6748
领域	气候变化 ; 资源环境
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文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/276702
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Wonchull Kang,Chi Chung Lee,Andrew J. Jasniewski,et al. Structural evidence for a dynamic metallocofactor during N₂ reduction by Mo-nitrogenase[J]. Science,2020.
APA	Wonchull Kang,Chi Chung Lee,Andrew J. Jasniewski,Markus W. Ribbe,&Yilin Hu.(2020).Structural evidence for a dynamic metallocofactor during N₂ reduction by Mo-nitrogenase.Science.
MLA	Wonchull Kang,et al."Structural evidence for a dynamic metallocofactor during N₂ reduction by Mo-nitrogenase".Science (2020).