Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autoinduction is a conserved mechanism of cell density-dependent gene regulation that occurs in a variety of gram-negative bacteria. Autoinducible luminescence in Vibrio fischeri requires a transcriptional activator, LuxR, while a LuxR homolog, LasR, activates elastase expression in Pseudomonas aeruginosa. Both LuxR and LasR require specific signal molecules, called autoinducers, for activity. We show here the activation in Escherichia coli of the V. fischeri luminescence (lux) operon by LasR and of the P. aeruginosa elastase gene (lasB) by LuxR when each is in the presence of its cognate autoinducer. Neither LuxR nor LasR showed appreciable activity with the heterologous V. fischeri or P. aeruginosa autoinducer. This supports the view that there is a direct interaction of each transcriptional activator with its proper autoinducer and suggests that there are conserved, autoinduction-related elements within the promoter regions of these genes.
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PMID:Interchangeability and specificity of components from the quorum-sensing regulatory systems of Vibrio fischeri and Pseudomonas aeruginosa. 818 10

The synthesis of proteins necessary for the respiratory reduction of nitrate to dinitrogen is induced in most denitrifying bacteria by a shift to anaerobiosis. A homolog of the fur gene, which encodes a redox-active transcriptional activator in Escherichia coli, was isolated from Pseudomonas stutzeri by using the anr gene of Pseudomonas aeruginosa as the hybridization probe (R. G. Sawers, Mol. Microbiol. 5:1469-1481, 1991). The coding region was located on a 3-kb SmaI fragment. An open reading frame of 735 nucleotides, designated fnrA, had the coding potential for a protein of 244 amino acids (M(r) = 27,089) with 51.2% positional identity to the Fnr protein of E. coli and 86.1% to the Anr protein of P. aeruginosa. The fnrA gene gave a single transcript of 0.85 kb and complemented nitrate-dependent anaerobic growth of an fnr deletion mutant of E. coli. An open reading frame immediately downstream of fnrA encoded adenine phosphoribosyltransferase (EC 2.4.2.7). Mutations in fnrA were generated in vitro by insertional mutagenesis followed by gene replacement. Gene inactivation was shown by loss of the fnrA transcript and detection of an arginine deiminase (EC 3.5.3.6)-negative phenotype in the mutants. However, neither the enzymatic activities nor the levels of anaerobic expression of the respiratory enzymes nitrate reductase (EC 1.7.99.4), nitrate reductase (EC 1.9.3.2), NO reductase (EC 1.7.99.7), and N2O reductase (EC 1.7.99.6) were changed in fnrA mutants versus the P. stutzeri wild type. A promoter-probe vector for Fnr-dependent transcription was activated anaerobically in the fnrA mutants, suggesting the existence of a second Fnr homolog in the same bacterium. The Fnr-binding motifs, apparent in the promoter region of genes encoding denitrification components of P. stutzeri, are likely to be recognized by this second Fnr homolog. Preliminary evidence indicates also the presence of the catabolite activator protein, Crp, in P. stutzeri.
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PMID:Anaerobic control of denitrification in Pseudomonas stutzeri escapes mutagenesis of an fnr-like gene. 822 70

Pseudomonas sp. strain CF600 can degrade phenol and some of its methylated derivatives via a plasmid (pVI150)-encoded pathway. The metabolic route involves hydroxylation by a multi-component phenol hydroxylase and a subsequent meta-cleavage pathway. All 15 structural genes involved are clustered in an operon that is regulated by a divergently transcribed transcriptional activator. The multi-component nature of the phenol hydroxylase is unusual since reactions of this type are usually accomplished by single component flavoproteins. We have isolated and analysed a number of marine bacterial isolates capable of degrading phenol and a range of other aromatic compounds as sole carbon and energy sources. Southern hybridization and enzyme assays were used to compare the catabolic pathways of these strains and of the archetypal phenol-degrader Pseudomonas U, with respect to known catabolic genes encoded by Pseudomonas CF600. All the strains tested that degraded phenol via a meta-cleavage pathway were found to have DNA highly homologous to each of the components of the multicomponent phenol hydroxylase. Moreover, DNA of the same strains also strongly hybridized to probes specific for pVI150-encoded meta-pathway genes and the specific regulator of its catabolic operon. These results demonstrate conservation of structural and regulatory genes involved in aromatic catabolism within strains isolated from diverse geographical locations (UK, Norway and USA) and a range of habitats that include activated sludge, sea water and fresh-water mud.
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PMID:Conservation of regulatory and structural genes for a multi-component phenol hydroxylase within phenol-catabolizing bacteria that utilize a meta-cleavage pathway. 827 53

The elastolytic activity of the opportunistic pathogen Pseudomonas aeruginosa is due to the combined activities of at least three secreted proteins: elastase, LasA and alkaline protease. Transcription of both the lasA gene and the elastase structural gene, lasB, requires the transcriptional activator LasR. In order to localize the promoter elements involved in lasA expression, the transcription start point (tsp) for lasA was localized by S1 protection and primer extension analysis. The DNA sequence of the region upstream from the tsp was determined, and a putative sigma promoter was identified. Sequence comparison with the lasB promoter region revealed two areas of considerable homology which could act as potential binding sites for LasR or other, as yet unidentified, regulatory proteins.
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PMID:Pseudomonas aeruginosa lasA gene: determination of the transcription start point and analysis of the promoter/regulatory region. 833 50

Phenotype conversion (PC) in Pseudomonas solanacearum is the coordinated change in production of extracellular polysaccharide and a variety of extracellular proteins, some of which contribute to virulence. Although PC is normally spontaneous, it is mimicked by transposon inactivation of the phcA locus (S. M. Brumbley and T. P. Denny, J. Bacteriol. 172:5677-5685, 1990). The DNA sequence of a 1.8-kb region from strain AW1 that contains phcA revealed one open reading frame that should encode a polypeptide of 38.6 kDa. The PhcA protein produced in Escherichia coli by using a T7 RNA polymerase expression system was of the predicted size. The deduced amino acid sequence of PhcA is similar to that of some members of the LysR transcriptional activator gene family, especially in the amino terminus, where a putative helix-turn-helix DNA-binding motif was identified. An analogous allele (phcA1) was cloned from the spontaneous PC mutant strain AW1-PC and found to be nonfunctional in complementation studies. When phcA1 was expressed in E. coli, the PhcA1 protein was 35.5 kDa, 3 kDa smaller than PhcA. Sequence analysis of phcA1 and chimeric constructs of phcA and phcA1 confirmed that PhcA1 is truncated by a 2-bp insertion 147 nucleotides upstream of the carboxyl terminus of PhcA. Southern blot analysis of 10 additional independently isolated PC mutants of strain AW1 revealed that two strains have larger insertions (0.2 and 1.0 kb) within phcA. These results suggest that phcA encodes a DNA-binding protein that regulates the transcription of one or more of the genes involved in P. solanacearum virulence and that spontaneous PC can be attributed to one of several different insertions within this locus.
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PMID:Phenotype conversion in Pseudomonas solanacearum due to spontaneous inactivation of PhcA, a putative LysR transcriptional regulator. 836 33

Pseudomonas aeruginosa K372 is deficient in the production of both the 75-kDa ferripyochelin receptor protein and pyochelin. A 1.8-kb EcoRI-SalI fragment which restored production of both the receptor protein and pyochelin was cloned. Nucleotide sequencing of the fragment revealed an open reading frame of 888 bp, designated pchR (pyochelin), capable of encoding a 296-amino-acid protein of a 32,339-Da molecular mass. By using a phage T7-based expression system, a protein of ca. 32 kDa was produced off the 1.8-kb fragment, confirming that this open reading frame was indeed expressed. A region exhibiting homology to the consensus Fur-binding site of Escherichia coli was identified upstream of the pchR coding region overlapping a putative promoter. In addition, the C-terminal 80 amino acid residues of PchR showed approximately 50% homology (identity, 31%; conserved changes, 19%) to the carboxy terminus of AraC, a known transcriptional activator of gene expression in E. coli, Salmonella typhimurium, Citrobacter freundii, and Erwinia chrysanthemi. Within the C-terminal region of PchR, AraC, and a number of other members of the AraC family of transcriptional activators, there exists a highly conserved 17-residue domain where, in fact, two residues are strictly maintained and two others exhibit only conserved changes, suggesting a common functional significance to this region in all of these proteins. These data are consistent with a role for PchR as a transcriptional activator of pyochelin and ferripyochelin receptor synthesis in P. aeruginosa. In agreement with this, a PchR mutant obtained by in vitro mutagenesis and gene replacement was deficient in production of the ferripyochelin receptor and pyochelin.
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PMID:Cloning and sequence analysis of a gene (pchR) encoding an AraC family activator of pyochelin and ferripyochelin receptor synthesis in Pseudomonas aeruginosa. 839 86

The lasR gene of Pseudomonas aeruginosa is required for transcription of the genes for elastase (lasB) and LasA protease (lasA), two proteases associated with virulence. We report here that the alkaline protease gene (apr) also requires the lasR gene for transcription. Alkaline protease mRNA was absent in the lasR mutant PAO-R1 and present when an intact lasR gene was supplied in trans as determined by Northern (RNA) analysis. The lasR gene also enhances exotoxin A production. Exotoxin A activity in supernatants of PAO-R1 were 30% less than in supernatants of the parental strain, PAO-SR. Multiple copies of lasR in trans in PAO-R1 in increased toxin A activity to twice the parental levels. Analysis of PAO-R1 containing the toxA promoter fused to beta-galactosidase suggests that LasR acts at the toxA promoter or at upstream toxA mRNA sequences. beta-Galactosidase activity was approximately 40% lower in PAO-R1 than in the parental strain, PAO-SR. Furthermore, the effect of LasR on the toxA promoter is not due to the stimulation of transcription of regA, a transcriptional activator of toxA. No difference in chloramphenicol acetyltransferase (CAT) activity was noted between PAO-SR and PAO-R1 containing transcriptional regA promoter-CAT gene fusions. These results broaden the regulatory dominion of lasR and suggest that the lasR gene plays a global role in P. aeruginosa pathogenesis.
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PMID:LasR of Pseudomonas aeruginosa is a transcriptional activator of the alkaline protease gene (apr) and an enhancer of exotoxin A expression. 845 22

Pseudomonas aeruginosa is an opportunistic human pathogen that causes a variety of infections in immunocompromised hosts and individuals with cystic fibrosis. Expression of elastase, one of the virulence factors produced by this organism, requires the transcriptional activator LasR. Experiments with gene fusions show that gene lasl is essential for high expression of elastase. The lasl gene is involved in the synthesis of a diffusible molecule termed Pseudomonas autoinducer (PAI). PAI provides P. aeruginosa with a means of cell-to-cell communication that is required for the expression of virulence genes and may provide a target for therapeutic approaches.
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PMID:Expression of Pseudomonas aeruginosa virulence genes requires cell-to-cell communication. 849 56

Active E1 component of Pseudomonas putida branched-chain-oxoacid dehydrogenase was purified from P. putida strains carrying pJRS84 which contains bkdR (encoding the transcriptional activator) and bkdA1 and bkdA2 (encoding the alpha and beta subunits). Expression was inducible, however, 45-, 39- and 37-kDa proteins were produced instead of the expected 45-kDa and 37-kDa proteins. The 45-kDa protein was identified as E1 alpha and the 37-kDa and 39-kDa proteins were identified as separate translational products of bkdA2 by their N-terminal sequences. The N-terminal amino acid of the 39-kDa protein was leucine instead of methionine. The 45-, 39- and 37-kDa proteins were also produced in wild-type P.putida. Translation of bkdA1 and bkdA2 from an Escherichia coli expression plasmid produced only 45-kDa and 39-kDa proteins, with N-terminal methionine on the 39-kDa protein. The insertion of guanine residues 5' to the first ATG of bkdA2 did not affect expression of E1 beta in P. putida including the N-terminal leucine which appears to eliminate the possibility of ribosome jumping. The Z-average molecular mass of the E1 component was determined by sedimentation equilibrium to be 172 +/- 9 kDa compared to a calculated value of 166 kDa for the heterotetramer and a Stokes radius of 5.1 nm. E1 alpha Ser313, which is homologous to the phosphorylated residue of rat liver E1 alpha, was converted to alanine resulting in about a twofold increase in Km, but no change in Kcat. S315A and S319A mutations had no effect on Km or Kcat indicating that these residues do not play a major part in catalysis of E1 alpha beta 2.
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PMID:Purification of active E1 alpha 2 beta 2 of Pseudomonas putida branched-chain-oxoacid dehydrogenase. 852 48

Pseudomonas putida PRS2000 degrades the aromatic acids benzoate and 4-hydroxybenzoate via two parallel sequences of reactions that converge at beta-ketoadipate, a derivative of which is cleaved to form tricarboxylic acid cycle intermediates. Structural genes (pca genes) required for the complete degradation of 4-hydroxybenzoate via the protocatechuate branch of the beta-ketoadipate pathway have been characterized, and a specific transport system for 4-hydroxybenzoate has recently been described. To better understand how P. putida coordinates the processes of 4-hydroxybenzoate transport and metabolism to achieve complete degradation, the regulation of pcaK, the 4-hydroxybenzoate transport gene, and that of pcaF, a gene required for both benzoate and 4-hydroxybenzoate degradation, were compared. Primer extension analysis and lacZ fusions showed that pcaK and pcaF, which are adjacent on the chromosome, are transcribed independently. PcaR, a transcriptional activator of several genes of the beta-ketoadipate pathway, is required for expression of both pcaF and pcaK, and the pathway intermediate beta-ketoadipate induces both genes. In addition to these expected regulatory elements, expression of pcaK, but not pcaF, is repressed by benzoate. This previously unrecognized layer of regulatory control in the beta-ketoadipate pathway appears to extend to the first two steps of 4-hydroxybenzoate degradation, since levels of 4-hydroxybenzoate hydroxylase and protocatechuate 3,4-dioxygenase activities were also depressed when cells were grown on a mixture of 4-hydroxybenzoate and benzoate. The apparent consequence of benzoate repression is that cells degrade benzoate in preference to 4-hydroxybenzoate. These findings indicate that 4-hydroxybenzoate transport is an integral feature of the beta-ketoadipate pathway in P. putida and that transport plays a role in establishing the preferential degradation of benzoate over 4-hydroxybenzoate. These results also demonstrate that there is communication between the two branches of the beta-ketoadipate pathway.
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PMID:Repression of 4-hydroxybenzoate transport and degradation by benzoate: a new layer of regulatory control in the Pseudomonas putida beta-ketoadipate pathway. 852 7


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