5n6y
From Proteopedia
Azotobacter vinelandii vanadium nitrogenase
Structural highlights
Function[VNFD_AZOVI] This vanadium-iron protein is part of the nitrogenase complex that catalyzes the key enzymatic reactions in nitrogen fixation. [VNFG_AZOVI] The key enzymatic reactions in nitrogen fixation are catalyzed by the nitrogenase complex, which has 2 components: the iron protein (component 2) and a component 1 which is either a molybdenum-iron protein, a vanadium-iron, or an iron-iron protein. [VNFK_AZOVI] This vanadium-iron protein is part of the nitrogenase complex that catalyzes the key enzymatic reactions in nitrogen fixation. Publication Abstract from PubMedNitrogenases catalyze the reduction of dinitrogen (N2) gas to ammonium at a complex heterometallic cofactor. This most commonly occurs at the FeMo cofactor (FeMoco), a [Mo-7Fe-9S-C] cluster whose exact reactivity and substrate-binding mode remain unknown. Alternative nitrogenases replace molybdenum with either vanadium or iron and differ in reactivity, most prominently in the ability of vanadium nitrogenase to reduce CO to hydrocarbons. Here we report the 1.35-A structure of vanadium nitrogenase from Azotobacter vinelandii. The 240-kDa protein contains an additional alpha-helical subunit that is not present in molybdenum nitrogenase. The FeV cofactor (FeVco) is a [V-7Fe-8S-C] cluster with a homocitrate ligand to vanadium. Unexpectedly, it lacks one sulfide ion compared to FeMoco, which is replaced by a bridging ligand, likely a mu-1,3-carbonate. The anion fits into a pocket within the protein that is obstructed in molybdenum nitrogenase, and its different chemical character helps to rationalize the altered chemical properties of this unique N2- and CO-fixing enzyme. The structure of vanadium nitrogenase reveals an unusual bridging ligand.,Sippel D, Einsle O Nat Chem Biol. 2017 Sep;13(9):956-960. doi: 10.1038/nchembio.2428. Epub 2017 Jul , 10. PMID:28692069[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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