Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.4 (nitrite reductase)
 1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The DNA sequence and derived amino-acid sequence of a 5618-base region in the 74-min area of the Escherichia coli chromosome has been determined in order to locate the structural gene, nirB, for the NADH-dependent nitrite reductase and a gene, cysG, required for the synthesis of the sirohaem prosthetic group. Three additional open reading frames, nirD, nirE and nirC, were found between nirB and cysG. Potential binding sites on the NirB protein for NADH and FAD, as well as conserved central core and interface domains, were deduced by comparing the derived amino-acid sequence with those of database proteins. A directly repeated sequence, which includes the motif -Cys-Xaa-Xaa-Cys-, is suggested as the binding site for either one [4Fe-4S] or two [2Fe-2S] clusters. The nirD gene potentially encodes a soluble, cytoplasmic protein of unknown function. No significant similarities were found between the derived amino-acid sequence of NirD and either NirB or any other protein in the database. If the nirE open reading frame is translated, it would encode a 33-amino-acid peptide of unknown function which includes 8 phenylalanyl residues. The product of the nirC gene is a highly hydrophobic protein with regions of amino-acid sequence similar to cytochrome oxidase polypeptide 1.
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PMID:Nucleotide sequence, organisation and structural analysis of the products of genes in the nirB-cysG region of the Escherichia coli K-12 chromosome. 220 Jun 72

Characterization of a nitrite reductase-negative Staphylococcus carnosus Tn917 mutant led to the identification of the nir operon, which encodes NirBD, the dissimilatory NADH-dependent nitrite reductase; SirA, the putative oxidase and chelatase, and SirB, the uroporphyrinogen III methylase, both of which are necessary for biosynthesis of the siroheme prosthetic group; and NirR, which revealed no convincing similarity to proteins with known functions. We suggest that NirR is essential for nir promoter activity. In the absence of NirR, a weak promoter upstream of sirA seems to drive transcription of sirA, nirB, nirD, and sirB in the stationary-growth phase. In primer extension experiments one predominant and several weaker transcription start sites were identified in the nir promoter region. Northern blot analyses indicated that anaerobiosis and nitrite are induction factors of the nir operon: cells grown aerobically with nitrite revealed small amounts of full-length transcript whereas cells grown anaerobically with or without nitrite showed large amounts of full-length transcript. Although a transcript is detectable, no nitrite reduction occurs in cells grown aerobically with nitrite, indicating an additional oxygen-controlled step at the level of translation, enzyme folding, assembly, or insertion of prosthetic groups. The nitrite-reducing activity expressed during anaerobiosis is switched off reversibly when the oxygen tension increases, most likely due to competition for electrons with the aerobic respiratory chain. Another gene, nirC, is located upstream of the nir operon. nirC encodes a putative integral membrane-spanning protein of unknown function. A nirC mutant showed no distinct phenotype.
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PMID:Molecular characterization of the nitrite-reducing system of Staphylococcus carnosus. 1004 79

In Staphylococcus carnosus, the nreABC (for nitrogen regulation) genes were identified and shown to link the nitrate reductase operon (narGHJI) and the putative nitrate transporter gene narT. An nreABC deletion mutant, m1, was dramatically affected in nitrate and nitrite reduction and growth. Transcription of narT, narGHJI, and the nitrite reductase (nir) operon was severely reduced even when cells were cultivated anaerobically without nitrate or nitrite. nreABC transcripts were detected when cells were grown aerobically or anaerobically with or without nitrate or nitrite. NreA is a GAF domain-containing protein of unknown function. In vivo and in vitro studies showed that NreC is phosphorylated by NreB and that phospho-NreC specifically binds to a GC-rich palindromic sequence to enhance transcription initiation. This binding motif was found at the narGHJI, nir, and narT promoters but not at the moeB promoter. NreB is a cytosolic protein with four N-terminal cysteine residues. The second cysteine residue was shown to be important for NreB function. In vitro autophosphorylation of NreB was not affected by nitrate, nitrite, or molybdate. The nir promoter activity was iron dependent. The data provide evidence for a global regulatory system important for aerobic and anaerobic metabolism, with NreB and NreC forming a classical two-component system and NreB acting as a sensor protein with oxygen as the effector molecule.
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PMID:The nitrate reductase and nitrite reductase operons and the narT gene of Staphylococcus carnosus are positively controlled by the novel two-component system NreBC. 1242 51

Rhizobium sullae strain HCNT1 contains a nitric oxide-producing nitrite reductase of unknown function due to the absence of a complementary nitric oxide reductase. HCNT1 had the ability to grow on selenite concentrations as high as 50 mM, and during growth, selenite was reduced to the less toxic elemental selenium. An HCNT1 mutant lacking nitrite reductase grew poorly in the presence of 5 mM selenite, was unable to grow in the presence of 25 or 50 mM selenite and also showed no evidence of selenite reduction. A naturally occurring nitrite reductase-deficient R. sullae strain, CC1335, also showed little growth on the higher concentrations of selenite. Mobilization of a plasmid containing the HCNT1 gene encoding nitrite reductase into CC1335 increased its resistance to selenite. To confirm that this ability to grow in the presence of high concentrations of selenite correlated with nitrite reductase activity, a new nitrite reductase-containing strain was isolated from the same location where HCNT1 was isolated. This strain was also resistant to high concentrations of selenite. Inactivation of the gene encoding nitrite reductase in this strain increased selenite sensitivity. These data suggest that the nitrite reductase of R. sullae provides resistance to selenite and offers an explanation for the radically truncated denitrification found uniquely in this bacterium.
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PMID:Selenite-reducing capacity of the copper-containing nitrite reductase of Rhizobium sullae. 1722 57

Pathways of electron transport to periplasmic nitrate (NapA) and nitrite (NrfA) reductases have been investigated in Campylobacter jejuni, a microaerophilic food-borne pathogen. The nap operon is unusual in lacking napC (encoding a tetra-haem c-type cytochrome) and napF, but contains a novel gene of unknown function, napL. The iron-sulphur protein NapG has a major role in electron transfer to the NapAB complex, but we show that slow nitrate-dependent growth of a napG mutant can be sustained by electron transfer from NrfH, the electron donor to the nitrite reductase NrfA. A napL mutant possessed approximately 50% lower NapA activity than the wild type but showed normal growth with nitrate as the electron acceptor. NrfA was constitutive and was shown to play a role in protection against nitrosative stress in addition to the previously identified NO-inducible single domain globin, Cgb. However, nitrite also induced cgb expression in an NssR-dependent manner, suggesting that growth of C. jejuni with nitrite causes nitrosative stress. This was confirmed by lack of growth of cgb and nssR mutants, and slow growth of the nrfA mutant, in media containing nitrite. Thus, NrfA and Cgb together provide C. jejuni with constitutive and inducible components of a robust defence against nitrosative stress.
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PMID:Growth of Campylobacter jejuni on nitrate and nitrite: electron transport to NapA and NrfA via NrfH and distinct roles for NrfA and the globin Cgb in protection against nitrosative stress. 1724 Dec 2

In 85-Mda plasmid (p85) of plant-associated bacteria Azospirillum brasilense Sp245 model strain, the genes encoding copper-containing nitrite reductase (nirK); heterodimeric NO-reductase (norCB); NorQ and NorD proteins affecting synthesis and (or) activation of NirK and (or) NO-reductase (norQD); catalytic subunit I ofcytochrom c oxidase (CccoN); presumable NO sensor carrying two hemeerythrine domains (orf181); and an enzyme required for synthesis of presumable NO antagonist, homocystein (metC) were identified. In the same region of p85, orf293 encoding transcriptional regulator of LysR type, orf208 whose protein product carries a formylmethanofuran dehydrogenase subunit E domain, and an orf164-encoding conservative secretory protein with unknown function were also found. Localization of a set of denitrification genes in the plasmid DNA A. brasilense Sp245 adjacent to IS elements ISAzba1 and ISAzba2 indicates potential mobility of these genes and high probability of their horizontal transfer among populations of rhizospheric bacteria. A site homologous to p85 nirK-orf208-orf181 genes was detected in the 115 kb plasmid of A. brasilense Sp7 type strain.
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PMID:[Localization of denitrification genes in plasmid DNA of bacteria Azospirillum brasilense]. 2079 94

Nitrate assimilation has been well studied for Gram-negative bacteria but not so much in the Gram-positive actinomycetes up to date. In a rifamycin SV-producing actinomycete, Amycolatopsis mediterranei strain U32, nitrate not only can be used as a sole nitrogen source but also remarkably stimulates the antibiotic production along with regulating the related metabolic enzymes. A gene cluster of nasACKBDEF was cloned from a U32 genomic library by in situ hybridization screening with a heterogeneous nasB probe and confirmed later by whole genome sequence, corresponding to the protein coding genes of AMED_1121 to AMED_1127. These genes were co-transcribed as an operon, concomitantly repressed by ammonium while activated with supplement of either nitrate or nitrite. Genetic and biochemical analyses identified the essential nitrate/nitrite assimilation functions of the encoded proteins, orderly, the assimilatory nitrate reductase catalytic subunit (NasA), nitrate reductase electron transfer subunit (NasC), nitrate/nitrite transporter (NasK), assimilatory nitrite reductase large subunit (NasB) and small subunit (NasD), bifunctional uroporphyrinogen-III synthase (NasE), and an unknown function protein (NasF). Comparing rifamycin SV production and the level of transcription of nasB and rifE from U32 and its individual nas mutants in Bennet medium with or without nitrate indicated that nitrate assimilation function encoded by the nas operon played an essential role in the "nitrate stimulated" rifamycin production but had no effect upon the transcription regulation of the primary and secondary metabolic genes related to rifamycin biosynthesis.
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PMID:Identification and functional analysis of a nitrate assimilation operon nasACKBDEF from Amycolatopsis mediterranei U32. 2142 91

Porphyromonas gingivalis, the causative agent of adult periodontitis, must maintain nitric oxide (NO) homeostasis and surmount nitric oxide stress from host immune responses or other oral bacteria to survive in the periodontal pocket. To determine the involvement of a putative hydroxylamine reductase (PG0893) and a putative nitrite reductase-related protein (PG2213) in P. gingivalis W83 NO stress resistance, genes encoding those proteins were inactivated by allelic exchange mutagenesis. The isogenic mutants P. gingivalis FLL455 (PG0893ermF) and FLL456 (PG2213ermF) were black pigmented and showed growth rates and gingipain and hemolytic activities similar to those of the wild-type strain. P. gingivalis FLL455 was more sensitive to NO than the wild type. Complementation of P. gingivalis FLL455 with the wild-type gene restored the level of NO sensitivity to a level similar to that of the parent strain. P. gingivalis FLL455 and FLL456 showed sensitivity to oxidative stress similar to that of the wild-type strain. DNA microarray analysis showed that PG0893 and PG2213 were upregulated 1.4- and 2-fold, respectively, in cells exposed to NO. In addition, 178 genes were upregulated and 201 genes downregulated more than 2-fold. The majority of these modulated genes were hypothetical or of unknown function. PG1181, predicted to encode a transcriptional regulator, was upregulated 76-fold. Transcriptome in silico analysis of the microarray data showed major metabolomic variations in key pathways. Collectively, these findings indicate that PG0893 and several other genes may play an important role in P. gingivalis NO stress resistance.
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PMID:Nitric oxide stress resistance in Porphyromonas gingivalis is mediated by a putative hydroxylamine reductase. 2224 13