Database accession: MF7000518
Name: Nitroreductase with bound acetate (Escherichia coli)
PDB ID: 1ylu
Experimental method: X-ray (2.00 Å)
Assembly: Homodimer
Source organism: Escherichia coli
Primary publication of the structure:
Race PR, Lovering AL, Green RM, Ossor A, White SA, Searle PF, Wrighton CJ, Hyde EI
Structural and mechanistic studies of Escherichia coli nitroreductase with the antibiotic nitrofurazone. Reversed binding orientations in different redox states of the enzyme.
(2005) J. Biol. Chem. 280: 13256-64
PMID: 15684426
Abstract:
The antibiotics nitrofurazone and nitrofurantoin are used in the treatment of genitourinary infections and as topical antibacterial agents. Their action is dependent upon activation by bacterial nitroreductase flavoproteins, including the Escherichia coli nitroreductase (NTR). Here we show that the products of reduction of these antibiotics by NTR are the hydroxylamine derivatives. We show that the reduction of nitrosoaromatics is enzyme-catalyzed, with a specificity constant approximately 10,000-fold greater than that of the starting nitro compounds. This suggests that the reduction of nitro groups proceeds through two successive, enzyme-mediated reactions and explains why the nitroso intermediates are not observed. The global reaction rate for nitrofurazone determined in this study is over 10-fold higher than that previously reported, suggesting that the enzyme is much more active toward nitroaromatics than previously estimated. Surprisingly, in the crystal structure of the oxidized NTR-nitrofurazone complex, nitrofurazone is oriented with its amide group, rather than the nitro group to be reduced, positioned over the reactive N5 of the FMN cofactor. Free acetate, which acts as a competitive inhibitor with respect to NADH, binds in a similar orientation. We infer that the orientation of bound nitrofurazone depends upon the redox state of the enzyme. We propose that the charge distribution on the FMN rings, which alters upon reduction, is an important determinant of substrate binding and reactivity in flavoproteins with broad substrate specificity.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
6,7-dihydropteridine reductase activity 6,7-dihydropteridine reductase activity
FMN binding FMN binding
identical protein binding identical protein binding
NAD(P)H dehydrogenase (quinone) activity NAD(P)H dehydrogenase (quinone) activity
oxidoreductase activity, acting on other nitrogenous compounds as donors, with NAD or NADP as acceptor oxidoreductase activity, acting on other nitrogenous compounds as donors, with NAD or NADP as acceptor
protein homodimerization activity protein homodimerization activity
Biological process:
2,4,6-trinitrotoluene catabolic process 2,4,6-trinitrotoluene catabolic process
Cellular component:
cytosol cytosol
membrane membrane
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: Oxygen-insensitive NAD(P)H nitroreductase
Source organism: Escherichia coli
Length: 217 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMDIISVALKRHSTKAFDASKKLTPEQAEQIKTLLQYSPSSTNSQPWHFIVASTEEGKARVAKSAAGNYVFNERKMLDASHVVVFCAKTAMDDVWLKLVVDQEDADGRFATPEAKAANDKGRKFFADMHRKDLHDDAEWMAKQVYLNVGNFLLGVAALGLDAVPIEGFDAAILDAEFGLKEKGYTSLVVVPVGHHSVEDFNATLPKSRLPQNITLTEV
UniProtKB AC: P38489 (positions: 2-217)
Coverage: 99%
Name: Oxygen-insensitive NAD(P)H nitroreductase
Source organism: Escherichia coli
Length: 217 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMDIISVALKRHSTKAFDASKKLTPEQAEQIKTLLQYSPSSTNSQPWHFIVASTEEGKARVAKSAAGNYVFNERKMLDASHVVVFCAKTAMDDVWLKLVVDQEDADGRFATPEAKAANDKGRKFFADMHRKDLHDDAEWMAKQVYLNVGNFLLGVAALGLDAVPIEGFDAAILDAEFGLKEKGYTSLVVVPVGHHSVEDFNATLPKSRLPQNITLTEV
UniProtKB AC: P38489 (positions: 2-217)
Coverage: 99%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: Nitroreductase family
Evidence level: Indirect evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
Authors claim that the homodimeric NAD(P)H nitroreductase is a highly intertwined dimer with the FMN binding site lying at the dimer interface (PMID:18241886). Other structures belonging to the nitroreductase family also have an extensive interaction surface wherein a large hydrophobic solvent-accessible surface becomes buried upon dimer formation, suggesting that the monomers would be unstable on their own (PMID:16229462, PMID:19436071). Domain-swapping is also typical, where the extended C-terminal region extensively interacts with the core domain of the neighbouring monomer, forming an interlocked dimer (PMID:34473996, PMID:19436071, PMID:8885832).
Chain A:
N/A
Chain B:
N/A
Surface and contacts features:
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). Download the CIF file (.cif)
Download this entry's XML file (.xml)
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