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)

The full elastolytic phenotype of Pseudomonas aeruginosa requires lasB, the structural gene for elastase, its transcriptional activator lasR, and lasA. The lasB gene was insertionally inactivated with the omega fragment and this mutated gene introduced into the P. aeruginosa chromosome. Replacement of the wild-type gene with the inactivated gene was verified by Southern analysis and confirmed by lack of elastase antigen on Western blots and lack of activity in liquid assays. The mutant did, however, retain elastolytic activity on elastin plates. This residual activity was abolished by inactivation of lasB in PAO-E64, a lasA-deficient mutant, demonstrating that it was due to the lasA gene product. Northern analysis demonstrated that, like lasB, lasA is transcriptionally controlled by the lasR gene product.
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PMID:Pseudomonas aeruginosa LasA: a second elastase under the transcriptional control of lasR. 176 76

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

The roles of the Pseudomonas aeruginosa proteases LasB (elastase) and LasA and the transcriptional activator LasR, which regulates the expression of these proteases, were evaluated in a murine model of P. aeruginosa corneal infection. In scarified corneas, P. aeruginosa PAO-A1 (LasA negative) or PAO-B1A1 (LasB and LasA negative) at a dose of 10(8) CFU per eye caused very mild or no disease following infection; however, the defect in PAO-A1 could not be complemented by supplying a functional copy of lasA either on a plasmid or inserted into the chromosome. In contrast, PAO-B1 (LasB negative) colonized the cornea and caused disease equal in severity to disease caused by the parental strain, PAO1-I. Although LasR is a known regulator of lasA expression, PAO-R1, a lasR-negative derivative of PAO1-I, was as virulent as the parental strain during corneal infection. When transcriptional fusion plasmids were used to quantify the expression of the lasB and lasA genes in P. aeruginosa PAO1-I and PAO-R1, the lasB::lacZ fusion in PAO-R1 showed only 3.5% as much activity as it did in PAO1-I, while the activity of the lasA::lacZ fusion in PAO-R1 was 27.8% of that in PAO1-I. Coadministration of 5 microg of purified LasA protease with PAO-A1 did not reconstitute a wild-type infection. This treatment produced an acute toxic reaction leading to prolonged eyelid closure without inflammatory destruction of the cornea that was similar to that observed when LasA was administered alone. These results indicate that insertional inactivation of lasA renders P. aeruginosa avirulent in a murine model of keratitis and that neither LasR nor elastase production is required for the establishment and maintenance of corneal infection. However, the lack of virulence of the LasA-deficient strains cannot be ascribed with certainty to the deficiency of LasA from the available data.
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PMID:Contribution of proteases and LasR to the virulence of Pseudomonas aeruginosa during corneal infections. 923 58

Pseudomonas aeruginosa PAO1 utilizes proline as the sole source of carbon and nitrogen via a bifunctional enzyme (the putA gene product) that has both proline dehydrogenase (EC 1.5.99.8) and pyrroline 5-carboxylate dehydrogenase (EC 1.5.1.12) activities. We characterized the pruR-putAP loci encoding the proline catabolic system of this strain. In contrast to the putA and putP (encoding proline permease) genes of other gram- negative bacteria, which are located at divergent or separate loci, Northern blotting demonstrated that the two genes form an operon in strain PAO1. While the phylogenetic lineage of the PutP protein of strain PAO1 was related to that of the origin (80% identity to the P. putida counterpart), PutA of PAO1 (PutA(PAO)) was rather distantly related (47% identity) to the P. putida counterpart. Moreover, unlike the PutA proteins of P. putida and enteric bacteria, PutA(PAO) appeared to lack a regulatory function. Upstream of the putAP operon, the divergent PA0781 gene specified a hypothetical outer membrane protein with a molecular weight of 74,202. This gene appeared to be dispensable for proline utilization as indicated by the normal growth of a knockout mutant of PA0781 on medium containing proline. The pruR (proline utilization regulator) gene immediately upstream of PA0781 encoded a transcriptional activator of the AraC/XylS protein family and mediated the proline-responsive expression of putAP. Primer extension studies identified a PruR-dependent promoter responsive to proline in the 5'-flanking region of putA. Thus, the proline utilization system of P. aeruginosa differs from that of P. putida with respect to putA structure, the organization of the putAP genes, and the regulatory mechanism of putA expression.
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PMID:Divergent structure and regulatory mechanism of proline catabolic systems: characterization of the putAP proline catabolic operon of Pseudomonas aeruginosa PAO1 and its regulation by PruR, an AraC/XylS family protein. 1227 Aug 21

Process of senescence includes multiple steps involving break-down of chlorophyll to degrade photosynthetic machinery. In this study, we showed that a stress-associated NAC transcription factor MpSNAC67 regulates senescence by promoting chlorophyll-catabolic genes. MpSNAC67 encodes a transcriptional activator and its promoter activity is restricted to vascular tissue of banana. Expression of MpSNAC67 showed positive responses to multiple abiotic stress conditions suggesting that MpSNAC67 is a stress associated NAC transcription factor. Transgenic banana lines overexpressing MpSNAC67 showed highly senesced phenotype including yellowing and de-greening of leaves similar to etiolated leaves. Transgenic leaves possessed low chlorophyll content and failed to retain normal chloroplast morphology including loss of granum thylakoid, non-uniform chloroplast membrane and increased number as well as size of plastoglobulins. In a gel shift assay MpSNAC67 could retard the mobility of chlorophyll catabolic genes such as PAO-like (Pheophorbide-a-oxygenase), HCAR-like (hydroxymethyl chlorophyll-a-reductase), NYC/NOL-like (Chlorophyll-b-reductase) as well as ORS1-like (a SenNAC). Expression of these genes were highly elevated in transgenic lines which indicate that MpSNAC67 is a positive regulator of senescence in banana and exercise its effect by regulating the expression of chlorophyll catabolic genes and ORS1.
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PMID:A stress associated NAC transcription factor MpSNAC67 from banana (Musa x paradisiaca) is involved in regulation of chlorophyll catabolic pathway. 3017 54