7NMP

E. coli NfsA with hydroquinone

Summary for 7NMP

• Entry DOI: 10.2210/pdb7nmp/pdb
• Related: 7NB9 7NIY
• Descriptor: Oxygen-insensitive NADPH nitroreductase, FLAVIN MONONUCLEOTIDE, DIMETHYL SULFOXIDE, ... (7 entities in total)
• Functional Keywords: complex with quinone product, flavoprotein, nitroreductase, oxidoreductase
• Biological source: Escherichia coli (strain K12)
• Total number of polymer chains: 1
• Total formula weight: 27698.91

Authors

Day, M.D.,Jarrom, D.,Parr, R.J.,Hyde, E.I.,White, S.A. (deposition date: 2021-02-23, release date: 2021-07-21, Last modification date: 2024-01-31)

Primary citation

Day, M.A.,Jarrom, D.,Christofferson, A.J.,Graziano, A.E.,Anderson, J.L.R.,Searle, P.F.,Hyde, E.I.,White, S.A.
The structures of E. coli NfsA bound to the antibiotic nitrofurantoin; to 1,4-benzoquinone and to FMN.
Biochem.J., 478:2601-2617, 2021

PubMed Abstract: 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.

PubMed: 34142705
DOI: 10.1042/BCJ20210160

Experimental method

X-RAY DIFFRACTION (1.25 Å)