6rk0

Structure of the Flavocytochrome Anf3 from Azotobacter vinelandii

spinqualitylabelsall models 6rk0, resolution 0.99Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6rk0 is a 2 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 0.99Å Ligands: FAD, HEM, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function C1DK98_AZOVD Publication Abstract from PubMed The biological route for nitrogen gas entering the biosphere is reduction to ammonia by the nitrogenase enzyme, which is inactivated by oxygen. Three types of nitrogenase exist, the least studied of which is the iron-only nitrogenase. The Anf3 protein in the bacterium Rhodobacter capsulatus is essential for diazotrophic (i.e. nitrogen-fixing) growth with the iron-only nitrogenase, but its enzymatic activity and function are unknown. Here, we biochemically and structurally characterize Anf3 from the model diazotrophic bacterium Azotobacter vinelandii. Determining the Anf3 crystal structure to atomic resolution, we observed that it is a dimeric flavocytochrome with an unusually close interaction between the heme and the flavin adenine dinucleotide cofactors. Measuring the reduction potentials by spectroelectrochemical redox titration, we observed values of -420 +/- 10 mV and -330 +/- 10 mV for the two FAD potentials and -340 +/- 1 mV for the heme. We further show that Anf3 accepts electrons from spinach ferredoxin and that Anf3 consumes oxygen without generating superoxide or hydrogen peroxide. We predict that Anf3 protects the iron-only nitrogenase from oxygen inactivation by functioning as an oxidase in respiratory protection, with flavodoxin or ferredoxin as the physiological electron donors. A low-potential terminal oxidase associated with the iron-only nitrogenase from the nitrogen-fixing bacterium Azotobacter vinelandii.,Varghese F, Kabasakal BV, Cotton CA, Schumacher J, Rutherford AW, Fantuzzi A, Murray JW J Biol Chem. 2019 May 1. pii: RA118.007285. doi: 10.1074/jbc.RA118.007285. PMID:31043481 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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