A novel NO‐responding regulator controls the reduction of nitric oxide in <i>Ralstonia eutropha</i>

Pohlmann, Anne; Cramm, Rainer; Schmelz, Karin; Friedrich, Bärbel

doi:10.1046/j.1365-2958.2000.02157.x

Cited by 108 publications

(127 citation statements)

References 68 publications

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“…NorR is a r 54 -dependent transcriptional activator that regulates expression of the NO reductase operons, norVW in E. coli and norAB in R. eutropha [21,22]. NorR binds to three tandem operator regions, inverted repeats with degenerate consensus GT-(N 7 )-AC, which are localized upstream of the r 54 promoter site [23].…”

Section: Norr Regulonmentioning

confidence: 99%

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Dissimilatory Metabolism of Nitrogen Oxides in Bacteria: Comparative Reconstruction of Transcriptional Networks

Rodionov¹,

Dubchak²,

Arkin³

et al. 2005

PLoS Comp Biol

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Bacterial response to nitric oxide (NO) is of major importance since NO is an obligatory intermediate of the nitrogen cycle. Transcriptional regulation of the dissimilatory nitric oxides metabolism in bacteria is diverse and involves FNRlike transcription factors HcpR, DNR, and NnrR; two-component systems NarXL and NarQP; NO-responsive activator NorR; and nitrite-sensitive repressor NsrR. Using comparative genomics approaches, we predict DNA-binding motifs for these transcriptional factors and describe corresponding regulons in available bacterial genomes. Within the FNR family of regulators, we observed a correlation of two specificity-determining amino acids and contacting bases in corresponding DNA recognition motif. Highly conserved regulon HcpR for the hybrid cluster protein and some other redox enzymes is present in diverse anaerobic bacteria, including Clostridia, Thermotogales, and delta-proteobacteria. NnrR and DNR control denitrification in alpha-and beta-proteobacteria, respectively. Sigma-54-dependent NorR regulon found in some gamma-and beta-proteobacteria contains various enzymes involved in the NO detoxification. Repressor NsrR, which was previously known to control only nitrite reductase operon in Nitrosomonas spp., appears to be the master regulator of the nitric oxides' metabolism, not only in most gamma-and beta-proteobacteria (including well-studied species such as Escherichia coli), but also in Gram-positive Bacillus and Streptomyces species. Positional analysis and comparison of regulatory regions of NO detoxification genes allows us to propose the candidate NsrRbinding motif. The most conserved member of the predicted NsrR regulon is the NO-detoxifying flavohemoglobin Hmp. In enterobacteria, the regulon also includes two nitrite-responsive loci, nipAB (hcp-hcr) and nipC (dnrN), thus confirming the identity of the effector, i.e. nitrite. The proposed NsrR regulons in Neisseria and some other species are extended to include denitrification genes. As the result, we demonstrate considerable interconnection between various nitrogen-oxides-responsive regulatory systems for the denitrification and NO detoxification genes and evolutionary plasticity of this transcriptional network.

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Section: Norr Regulonmentioning

confidence: 99%

“…Another NO-responsive transcriptional factor, r 54 -dependent NorR, activates expression of the NO reductases norVW in E. coli and norAB in R. eutropha [21,22]. Three tandem upstream activator sites with the core consensus GT-(N 7 )-AC were identified as NorR-binding sites observed in both promoter regions.…”

Section: Introductionmentioning

confidence: 96%

Dissimilatory Metabolism of Nitrogen Oxides in Bacteria: Comparative Reconstruction of Transcriptional Networks

Rodionov¹,

Dubchak²,

Arkin³

et al. 2005

PLoS Comp Biol

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“…The ytfE homologue of Salmonella enterica serovar Typhimurium (designated nipC) was identified in a screen for promoters inducible by acidified nitrite (23). Homologues of ytfE are also NO inducible in the denitrifying organisms Ralstonia eutropha and Pseudomonas stutzeri, which make NO as an intermediate of denitrification (29,44). Despite its widespread nature and conserved expression pattern, the function of the ytfE gene product remains unknown.…”

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confidence: 99%

The yjeB ( nsrR ) Gene of Escherichia coli Encodes a Nitric Oxide-Sensitive Transcriptional Regulator

2006

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Microarray studies of the Escherichia coli response to nitric oxide and nitrosative stress have suggested that additional transcriptional regulators of this response remain to be characterized. We identify here the product of the yjeB gene as a negative regulator of the transcription of the ytfE, hmpA and ygbA genes, all of which are known to be upregulated by nitrosative stress. Transcriptional fusions to the promoters of these genes were expressed constitutively in a yjeB mutant, indicating that all three are targets for repression by YjeB. An inverted repeat sequence that overlaps the ؊10 element of all three promoters is proposed to be a binding site for the YjeB protein. A similar inverted repeat sequence was identified in the tehA promoter, which is also known to be sensitive to nitrosative stress. The ytfE, hmpA, ygbA, and tehA promoters all caused derepression of a ytfE-lacZ transcriptional fusion when present in the cell in multiple copies, presumably by a repressor titration effect, suggesting the presence of functional YjeB binding sites in these promoters. However, YjeB regulation of tehA was weak, as judged by the activity of a tehA-lacZ fusion, perhaps because YjeB repression of tehA is masked by other regulatory mechanisms. Promoters regulated by YjeB could be derepressed by iron limitation, which is consistent with an iron requirement for YjeB activity. The YjeB protein is a member of the Rrf2 family of transcriptional repressors and shares three conserved cysteine residues with its closest relatives. We propose a regulatory model in which the YjeB repressor is directly sensitive to nitrosative stress. On the basis of similarity to the nitrite-responsive repressor NsrR from Nitrosomonas europaea, we propose that the yjeB gene of E. coli be renamed nsrR.

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“…The E. coli norR (ygaA) gene encodes a homolog of the NO-modulated NorR1 and NorR2 regulators of Ralstonia eutrophus (21), and is required for the induction of norV-lacZ fusions (15,16,22). In E. coli, the NO-induction of the hmpA gene was reported to be dependent on MetR, a transcriptional regulator of the methionine biosynthetic pathway, under aerobic conditions (23) and on FNR, an oxygen-responsive regulator, under anaerobic conditions (24).…”

mentioning

confidence: 99%

Prominent roles of the NorR and Fur regulators in the Escherichia coli transcriptional response to reactive nitrogen species

Mukhopadhyay

Zheng

Bedzyk

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

196

213

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We examined the genomewide transcriptional responses of Escherichia coli treated with nitrosylated glutathione or the nitric oxide (NO)-generator acidified sodium nitrite (NaNO 2) during aerobic growth. These assays showed that NorR, a homolog of NOresponsive transcription factors in Ralstonia eutrophus, and Fur, the global repressor of ferric ion uptake, are major regulators of the response to reactive nitrogen species. In contrast, SoxR and OxyR, regulators of the E. coli defenses against superoxide-generating compounds and hydrogen peroxide, respectively, have minor roles. Moreover, additional regulators of the E. coli response to reactive nitrogen species remain to be identified because several of the induced genes were regulated normally in norR, fur, soxRS, and oxyR mutant strains. We propose that the E. coli transcriptional response to reactive nitrogen species is a composite response mediated by the modification of multiple transcription factors containing iron or redox-active cysteines, some specifically designed to sense NO and its derivatives and others that are collaterally activated by the reactive nitrogen species.

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A novel NO‐responding regulator controls the reduction of nitric oxide in Ralstonia eutropha

Cited by 108 publications

References 68 publications

Dissimilatory Metabolism of Nitrogen Oxides in Bacteria: Comparative Reconstruction of Transcriptional Networks

Dissimilatory Metabolism of Nitrogen Oxides in Bacteria: Comparative Reconstruction of Transcriptional Networks

The yjeB ( nsrR ) Gene of Escherichia coli Encodes a Nitric Oxide-Sensitive Transcriptional Regulator

Prominent roles of the NorR and Fur regulators in the Escherichia coli transcriptional response to reactive nitrogen species

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