The homologous regulators ANR of Pseudornonas aeruginosa and FNR of Escherichia coli have overlapping but distinct specificities for anaerobically inducible promoters

Winteler, Harald V.; Haas, Dieter

doi:10.1099/13500872-142-3-685

Cited by 56 publications

(61 citation statements)

References 45 publications

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“…hcn promoter both had a canonical distance of 42.5 bp from the respective transcription start sites, T1 and T2 (17,53,58). Interestingly, there is a second, less conserved lux box-like sequence (designated ␤ in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…It is interesting to compare the role of ANR as an activator of the arc and hcn promoters. At the arc promoter, ANR and the ANR box (located at Ϫ41.5 bp from the transcriptional start site) are sufficient to give strong anaerobic activation (25,58). In the presence of arginine, the ArgR regulatory protein boosts the expression of the arc promoter by binding to the Ϫ70 region (35).…”

Section: Discussionmentioning

confidence: 99%

“…ANR belongs to the FNR (fumarate and nitrate reductase regulator) family of transcriptional regulators (53); anr mutants of both species produce little HCN (34,62). ANR can activate target promoters by binding to conserved sequences known as ANR boxes, with a recognition specificity which is similar but not identical to that of FNR (58).…”

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confidence: 99%

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Transcriptional Control of the Hydrogen Cyanide Biosynthetic Genes hcnABC by the Anaerobic Regulator ANR and the Quorum-Sensing Regulators LasR and RhlR in Pseudomonas aeruginosa

2000

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Virulence factors of Pseudomonas aeruginosa include hydrogen cyanide (HCN). This secondary metabolite is maximally produced at low oxygen tension and high cell densities during the transition from exponential to stationary growth phase. The hcnABC genes encoding HCN synthase were identified on a genomic fragment complementing an HCN-deficient mutant of P. aeruginosa PAO1. The hcnA promoter was found to be controlled by the FNR-like anaerobic regulator ANR and by the quorum-sensing regulators LasR and RhlR. Primer extension analysis revealed two transcription starts, T1 and T2, separated by 29 bp. Their function was confirmed by transcriptional lacZ fusions. The promoter sequence displayed an FNR/ANR box at ؊42.5 bp upstream of T2 and a lux box centered around ؊42.5 bp upstream of T1. Expression of the hcn genes was completely abolished when this lux box was deleted or inactivated by two point mutations in conserved nucleotides. The lux box was recognized by both LasR [activated by N-(oxododecanoyl)-homoserine lactone] and RhlR (activated by N-butanoyl-homoserine lactone), as shown by expression experiments performed in quorum-sensing-defective P. aeruginosa mutants and in the N-acyl-homoserine lactone-negative heterologous host P. fluorescens CHA0. A second, less conserved lux box lying 160 bp upstream of T1 seems to account for enhanced quorum-sensing-dependent expression. Without LasR and RhlR, ANR could not activate the hcn promoter. Together, these data indicate that expression of the hcn promoter from T1 can occur under quorum-sensing control alone. Enhanced expression from T2 appears to rely on a synergistic action between LasR, RhlR, and ANR.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Transcriptional Control of the Hydrogen Cyanide Biosynthetic Genes hcnABC by the Anaerobic Regulator ANR and the Quorum-Sensing Regulators LasR and RhlR in Pseudomonas aeruginosa

2000

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“…ArgR and AhrC repress their own expression (25) and activate the transcription of arginine catabolic genes by interacting with other regulation factors, such as ANR and RocR of E. coli and Bacillus subtilis, respectively (14,27,50).…”

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ArgR and AhrC Are Both Required for Regulation of Arginine Metabolism in Lactococcus lactis

et al. 2004

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The DNA binding proteins ArgR and AhrC are essential for regulation of arginine metabolism in Escherichia coli and Bacillus subtilis, respectively. A unique property of these regulators is that they form hexameric protein complexes, mediating repression of arginine biosynthetic pathways as well as activation of arginine catabolic pathways. The gltS-argE operon of Lactococcus lactis encodes a putative glutamate or arginine transport protein and acetylornithine deacetylase, which catalyzes an important step in the arginine biosynthesis pathway. By random integration knockout screening we found that derepression mutants had ISS1 integrations in, among others, argR and ahrC. Single as well as double regulator deletion mutants were constructed from Lactococcus lactis subsp. cremoris MG1363. The three arginine biosynthetic operons argCJDBF, argGH, and gltS-argE were shown to be repressed by the products of argR and ahrC. Furthermore, the arginine catabolic arcABD1C1C2TD2 operon was activated by the product of ahrC but not by that of argR. Expression from the promoter of the argCJDBF operon reached similar levels in the single mutants and in the double mutant, suggesting that the regulators are interdependent and not able to complement each other. At the same time they also appear to have different functions, as only AhrC is involved in activation of arginine catabolism. This is the first study where two homologous arginine regulators are shown to be involved in arginine regulation in a prokaryote, representing an unusual mechanism of regulation.Arginine, a nonessential amino acid in the lactic acid bacterium Lactococcus lactis, is synthesized de novo from glutamate in eight enzymatic steps (Fig. 1). The recent publication of the L. lactis genome sequence (5) has revealed that the putative arginine biosynthesis genes are encoded by the three operons argCJDBF, gltS-argE, and argGH. The products of these genes all show homology to known arginine biosynthetic enzymes, except for that of gltS, which has been annotated as a putative glutamate or arginine ABC transporter (5). While the biosynthetic genes have been shown to be regulated by the presence of arginine in other organisms, this has not been investigated in lactic acid bacteria (LAB). The activities of the biosynthetic enzymes have been shown to be repressed by arginine in Lactobacillus plantarum (6), but regulatory studies on the transcriptional level have not been performed on LAB.Mechanisms for arginine catabolism vary among organisms (1). In L. lactis, complete degradation of arginine into ornithine, ammonium, and carbon dioxide takes place via the arginine deiminase pathway (ADI pathway) in three enzymatic steps catalyzed by arginine deiminase (ArcA), ornithine carbamoyltransferase (ArcB), and carbamate kinase (ArcC) (Fig. 1). The genes arcA, arcB, arcC1, and arcC2 encoding these enzymes are located in the arcABD1C1C2TD2 gene cluster. L. lactis harbors an extra arcC homologue, called arcC3, which is located distant from the remainder of the arginine-related ge...

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“…The arginine deiminase pathway functions to provide P. aeruginosa with energy in the absence of appropriate terminal electron acceptors (43). The anr gene of P. aeruginosa appears to be a close relative of fnr of Escherichia coli (49); in fact, the two genes can replace each other in heterologous systems (15). In contrast to the current understanding of the molecular basis for control of the arginine deiminase pathway, analogous information is lacking regarding the AST pathway (Fig.…”

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Cloning and characterization of argR, a gene that participates in regulation of arginine biosynthesis and catabolism in Pseudomonas aeruginosa PAO1

Park

Abdelal

1997

J Bacteriol

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Gel retardation experiments indicated the presence in Pseudomonas aeruginosa cell extracts of an arginineinducible DNA-binding protein that interacts with the control regions for the car and argF operons, encoding carbamoylphosphate synthetase and anabolic ornithine carbamoyltransferase, respectively. Both enzymes are required for arginine biosynthesis. The use of a combination of transposon mutagenesis and arginine hydroxamate selection led to the isolation of a regulatory mutant that was impaired in the formation of the DNA-binding protein and in which the expression of an argF::lacZ fusion was not controlled by arginine. Experiments with various subclones led to the conclusion that the insertion affected the expression of an arginine regulatory gene, argR, that encodes a polypeptide with significant homology to the AraC/XylS family of regulatory proteins. Determination of the nucleotide sequence of the flanking regions showed that argR is the sixth and terminal gene of an operon for transport of arginine. The argR gene was inactivated by gene replacement, using a gentamicin cassette. Inactivation of argR abolished arginine control of the biosynthetic enzymes encoded by the car and argF operons. Furthermore, argR inactivation abolished the induction of several enzymes of the arginine succinyltransferase pathway, which is considered the major route for arginine catabolism under aerobic conditions. Consistent with this finding and unlike the parent strain, the argR::Gm derivative was unable to utilize arginine or ornithine as the sole carbon source. The combined data indicate a major role for ArgR in the control of arginine biosynthesis and aerobic catabolism.Arginine metabolism is of considerable significance in Pseudomonas aeruginosa, which can utilize this amino acid as a good source of carbon, nitrogen, and energy (16). The significance of arginine as a nutrient to P. aeruginosa is reflected in its being one of the strongest chemotactic attractants for this organism (10). This significance is also reflected in the presence of four catabolic pathways for the utilization of arginine ( Fig. 1) (16): the arginine deiminase pathway, the arginine succinyltransferase (AST) pathway; the arginine dehydrogenase pathway, and the arginine decarboxylase pathway.Recent work by Haas and coworkers has elucidated the role of anr (for anaerobic regulation) in induction of the arginine deiminase pathway by low oxygen tension (15). The arginine deiminase pathway functions to provide P. aeruginosa with energy in the absence of appropriate terminal electron acceptors (43). The anr gene of P. aeruginosa appears to be a close relative of fnr of Escherichia coli (49); in fact, the two genes can replace each other in heterologous systems (15). In contrast to the current understanding of the molecular basis for control of the arginine deiminase pathway, analogous information is lacking regarding the AST pathway (Fig. 1). This pathway, which converts arginine to glutamate, is considered the major route for catabolism in P. aeruginosa u...

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The homologous regulators ANR of Pseudornonas aeruginosa and FNR of Escherichia coli have overlapping but distinct specificities for anaerobically inducible promoters

Cited by 56 publications

References 45 publications

Transcriptional Control of the Hydrogen Cyanide Biosynthetic Genes hcnABC by the Anaerobic Regulator ANR and the Quorum-Sensing Regulators LasR and RhlR in Pseudomonas aeruginosa

Transcriptional Control of the Hydrogen Cyanide Biosynthetic Genes hcnABC by the Anaerobic Regulator ANR and the Quorum-Sensing Regulators LasR and RhlR in Pseudomonas aeruginosa

ArgR and AhrC Are Both Required for Regulation of Arginine Metabolism in Lactococcus lactis

Cloning and characterization of argR, a gene that participates in regulation of arginine biosynthesis and catabolism in Pseudomonas aeruginosa PAO1

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