7nb9 | pdb_00007nb9

E. coli NfsA with nitrofurantoin

spinqualitylabelsall models 7nb9, resolution 1.09Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7nb9 is a 1 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.09Å Ligands: DMS, FMN, U6Z Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NFSA_ECOLI Reduction of nitroaromatic compounds using NADH. Reduces nitrofurazone by a ping-pong bi-bi mechanism possibly to generate a two-electron transfer product. Major component of the oxygen-insensitive nitroreductase activity in E.coli. Publication Abstract from PubMed NfsA is a dimeric flavoprotein that catalyses the reduction in nitroaromatics and quinones by NADPH. This reduction is required for the activity of nitrofuran antibiotics. The crystal structure of free Escherichia coli NfsA and several homologues have been determined previously, but there is no structure of the enzyme with ligands. We present here crystal structures of oxidised E. coli NfsA in the presence of several ligands, including the antibiotic nitrofurantoin. Nitrofurantoin binds with the furan ring, rather than the nitro group that is reduced, near the N5 of the FMN. Molecular dynamics simulations show that this orientation is only favourable in the oxidised enzyme, while potentiometry suggests that little semiquinone is formed in the free protein. This suggests that the reduction occurs by direct hydride transfer from FMNH- to nitrofurantoin bound in the reverse orientation to that in the crystal structure. We present a model of nitrofurantoin bound to reduced NfsA in a viable hydride transfer orientation. The substrate 1,4-benzoquinone and the product hydroquinone are positioned close to the FMN N5 in the respective crystal structures with NfsA, suitable for reaction, but are mobile within the active site. The structure with a second FMN, bound as a ligand, shows that a mobile loop in the free protein forms a phosphate-binding pocket. NfsA is specific for NADPH and a similar conformational change, forming a phosphate-binding pocket, is likely to also occur with the natural cofactor. The structures of E. coli NfsA bound to the antibiotic nitrofurantoin; to 1,4-benzoquinone and to FMN.,Day MA, Jarrom D, Christofferson AJ, Graziano AE, Anderson JLR, Searle PF, Hyde EI, White SA Biochem J. 2021 Jul 16;478(13):2601-2617. doi: 10.1042/BCJ20210160. PMID:34142705 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Nitroreductase 3D structures

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