8e3u

Nickel-reconstituted nitrogenase MoFeP mutant S188A from Azotobacter vinelandii after IDS oxidation

spinqualitylabelsall models 8e3u, resolution 1.99Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8e3u is a 4 chain structure with sequence from Azotobacter vinelandii DJ. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.99Å Ligands: FE, HCA, ICS, NA, UFF Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NIFD_AZOVI This molybdenum-iron protein is part of the nitrogenase complex that catalyzes the key enzymatic reactions in nitrogen fixation. Publication Abstract from PubMed Nitrogenase catalyzes the multielectron reduction of dinitrogen to ammonia. Electron transfer in the catalytic protein (MoFeP) proceeds through a unique [8Fe-7S] cluster (P-cluster) to the active site (FeMoco). In the reduced, all-ferrous (P(N)) state, the P-cluster is coordinated by six cysteine residues. Upon two-electron oxidation to the P(2+) state, the P-cluster undergoes conformational changes in which a highly conserved oxygen-based residue (a Ser or a Tyr) and a backbone amide additionally ligate the cluster. Previous studies of Azotobacter vinelandii (Av) MoFeP revealed that when the oxygen-based residue, betaSer188, was mutated to a noncoordinating residue, Ala, the P-cluster became redox-labile and reversibly lost two of its eight Fe centers. Surprisingly, the Av strain with a MoFeP variant that lacked the serine ligand (Av betaSer188Ala MoFeP) displayed the same diazotrophic growth and in vitro enzyme turnover rates as wild-type Av MoFeP, calling into question the necessity of this conserved ligand for nitrogenase function. Based on these observations, we hypothesized that betaSer188 plays a role in protecting the P-cluster under nonideal conditions. Here, we investigated the protective role of betaSer188 both in vivo and in vitro by characterizing the ability of Av betaSer188Ala cells to grow under suboptimal conditions (high oxidative stress or Fe limitation) and by determining the tendency of betaSer188Ala MoFeP to be mismetallated in vitro. Our results demonstrate that betaSer188 (1) increases Av cell survival upon exposure to oxidative stress in the form of hydrogen peroxide, (2) is necessary for efficient Av diazotrophic growth under Fe-limiting conditions, and (3) may protect the P-cluster from metal exchange in vitro. Taken together, our findings suggest a structural adaptation of nitrogenase to protect the P-cluster via Ser ligation, which is a previously unidentified functional role of the Ser residue in redox proteins and adds to the expanding functional roles of non-Cys ligands to FeS clusters. Role of Serine Coordination in the Structural and Functional Protection of the Nitrogenase P-Cluster.,Rutledge HL, Field MJ, Rittle J, Green MT, Tezcan FA J Am Chem Soc. 2022 Dec 7;144(48):22101-22112. doi: 10.1021/jacs.2c09480. Epub , 2022 Nov 29. PMID:36445204 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nitrogenase 3D structures

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