Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In previous reports from our laboratory, the three structural genes (NQO1, NQO2, and NQO3) of the energy-transducing NADH-quinone oxidoreductase of Paracoccus denitrificans were characterized [Xu, X., Matsuno-Yagi, A., & Yagi, T. (1991) Biochemistry 30, 6422-6428; (1991) Biochemistry 30, 8678-8684; (1992) Arch. Biochem. Biophys. 296, 40-48]. In this report, the four structural genes NQO4, NQO5, NQO6, and NQO7 of the same Paracoccus denitrificans oxidoreductase were cloned and sequenced. On the basis of sequence homology and immunological cross-reactivity, these genes encode counterparts of the 49-, 30-, and 20-kDa polypeptides and the mitochondrial DNA ND3 polypeptides of bovine mitochondrial complex I. These seven structural genes were found to be located in the same gene cluster. The order of the seven structural genes of the Paracoccus NADH-quinone oxidoreductase in the gene cluster is NQO7, NQO6, NQO5, NQO4, NQO2, NQO1, and NQO3. Upstream of the NQO7 gene, an open reading frame encoding a predicted polypeptide homologous to the UV repair enzyme A of Escherichia coli and Micrococcus lysodeikticus was detected. The 5'-terminus of the gene cluster carrying the Paracoccus NADH-quinone oxidoreductase was studied, and the possible promoter region is discussed. The NQO4 and NQO5 genes appear to code for the M(r) 48,000 and 21,000 polypeptides of the isolated Paracoccus NADH dehydrogenase complex [Yagi, T. (1986) Arch. Biochem. Biophys. 250, 302-311] on the basis of amino acid analyses and N-terminal protein sequence analyses. The antisera to the bovine complex I 49- and 30-kDa polypeptides cross-reacted with the Paracoccus 48- and 21-kDa subunits, respectively.
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PMID:Gene cluster of the energy-transducing NADH-quinone oxidoreductase of Paracoccus denitrificans: characterization of four structural gene products. 163 25

The NADH dehydrogenase complex isolated from Paracoccus denitrificans is composed of approximately 10 unlike polypeptides [Yagi, T. (1986) Arch. Biochem. Biophys. 250, 302-311]. Structural genes encoding the subunits of this enzyme complex constitute at least one gene cluster [Xu, X., Matsuno-Yagi, A., & Yagi, T. (1991) Biochemistry 30, 6422-6428]. The 25-kDa subunit (NQO2), which has been isolated from sodium dodecyl sulfate-polyacrylamide gels, is a polypeptide of this enzyme complex. The partial N-terminal amino acid sequence and amino acid composition of the NQO2 subunit have been determined. On the basis of the amino acid sequence, the NQO2 gene was found to be located 1.7 kilobase pairs upstream of the gene for NADH-binding subunit (NQO1). The complete nucleotide sequence of the NQO2 gene was determined. It is composed of 717 base pairs and codes for 239 amino acid residues with a calculated molecular weight of 26,122. The NQO2 subunit is homologous to the Mr 24,000 subunit of the mammalian mitochondrial NADH-ubiquinone oxidoreductase which bears an electron paramagnetic resonance-visible binuclear iron-sulfur cluster (probably cluster N1b). Comparison of the predicted amino acid sequence of the Paracoccus NQO2 subunit with those of its mammalian counterparts suggests putative binding sites for the iron-sulfur cluster. In addition, nucleotide sequencing shows the presence of two unidentified reading frames between the NQO1 and NQO2 genes. These are designated URF1 and URF2 and are composed of 261 and 642 base pairs, respectively. The possible function of the protein coded for the URF2 is discussed.
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PMID:Characterization of the 25-kilodalton subunit of the energy-transducing NADH-ubiquinone oxidoreductase of Paracoccus denitrificans: sequence similarity to the 24-kilodalton subunit of the flavoprotein fraction of mammalian complex I. 190 71

We have cloned and sequenced the mouse NMO1 cDNA, which encodes the NAD(P)H:menadione oxidoreductase [also called NAD(P)H:(quinone acceptor) oxidoreductase; quinone reductase; azo dye reductase; DT diaphorase; EC 1.6.99.2]. The cDNA is 1528 bp in length excluding the poly(A+) tail, and has 5' and 3' nontranslated regions of 108 bp and 595 bp, respectively. The deduced protein contains 274 amino acids, including the first methionine (M(r) = 30,959). The mouse NMO1 protein is: 94% similar to the rat NMO1 and 86.5% to the human NMO1 proteins; 49.3% identical to the human NQO2 protein; and < 20% similar to several dozen other proteins in the quinone oxidoreductase superfamily. Southern hybridization analysis of mouse DNA reveals that the Nmo1 gene is likely to span less than a total of 20 kb. The Nmo1 gene is highly inducible by 2,3,7,8,-tetrachlorodibenzo-p-dioxin (dioxin; TCDD) in mouse liver and mouse cell cultures. TCDD inducibility of NMO1 is detectable at 12 and 18 days of gestation, but markedly elevated at 1-3 weeks post partum as compared with the 6- and 12-week-old mouse. NMO1 mRNA levels are strikingly elevated in the untreated mouse hepatoma Hepa-1c1c7 mutant line c37 lacking CYP1A1 (aryl hydrocarbon hydroxylase) activity, and in the untreated 14CoS/14CoS mouse cell line having an 'oxidative stress response' caused by homozygous deletion of about 3800 kb on chromosome 7. Previous work and the data in this report show that the murine Nmo1 gene is regulated by three distinct mechanisms: CYP1A1 metabolism-dependent repression, Ah receptor-mediated induction by TCDD, and activation by the chromosome 7-mediated oxidative stress response.
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PMID:Mouse dioxin-inducible NAD(P)H: menadione oxidoreductase: NMO1 cDNA sequence and genetic differences in mRNA levels. 770 40

Complex I (NADH-quinone oxidoreductase) is an enzyme that catalyzes the initial electron transfer from nicotinamide adenine dinucleotide (NADH) to flavin mononucleotide (FMN) bound at the tip of the hydrophilic domain of complex I. The electron flow into complex I is coupled to the generation of a proton gradient across the membrane that is essential for the synthesis of ATP. However, Helicobacter pylori has an unusual complex I that lacks typical NQO1 and NQO2 subunits, both of which are generally included in the NADH dehydrogenase domain of complex I. Here, we determined the solution structure of HP1264, one of the unusual subunits of complex I from H. pylori, which is located in place of NQO2, by three-dimensional nuclear magnetic resonance (NMR) spectroscopy and revealed that HP1264 can bind to FMN through UV-visible, fluorescence, and NMR titration experiments. This result suggests that FMN-bound HP1264 could be involved in the initial electron transfer step of complex I. In addition, HP1264 is structurally most similar to Escherichia coli TusA, which belongs to the SirA-like superfamily having an IF3-like fold in the SCOP database, implying that HP1264 adopts a novel fold for FMN binding. On the basis of the NMR titration data, we propose the candidate residues Ile32, Met34, Leu58, Trp68, and Val71 of HP1264 for the interaction with FMN. Notably, these residues are not conserved in the FMN binding site of any other flavoproteins with known structure. This study of the relationship between the structure and FMN binding property of HP1264 will contribute to improving our understanding of flavoprotein structure and the electron transfer mechanism of complex I.
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PMID:Structural characterization of HP1264 reveals a novel fold for the flavin mononucleotide binding protein. 2340 39