Dataset Information

The pvc operon regulates the expression of the Pseudomonas aeruginosa fimbrial chaperone/usher pathway (cup) genes.

ABSTRACT: The Pseudomonas aeruginosa fimbrial structures encoded by the cup gene clusters (cupB and cupC) contribute to its attachment to abiotic surfaces and biofilm formation. The P. aeruginosa pvcABCD gene cluster encodes enzymes that synthesize a novel isonitrile functionalized cumarin, paerucumarin. Paerucumarin has already been characterized chemically, but this is the first report elucidating its role in bacterial biology. We examined the relationship between the pvc operon and the cup gene clusters in the P. aeruginosa strain MPAO1. Mutations within the pvc genes compromised biofilm development and significantly reduced the expression of cupB1-6 and cupC1-3, as well as different genes of the cupB/cupC two-component regulatory systems, roc1/roc2. Adjacent to pvc is the transcriptional regulator ptxR. A ptxR mutation in MPAO1 significantly reduced the expression of the pvc genes, the cupB/cupC genes, and the roc1/roc2 genes. Overexpression of the intact chromosomally-encoded pvc operon by a ptxR plasmid significantly enhanced cupB2, cupC2, rocS1, and rocS2 expression and biofilm development. Exogenously added paerucumarin significantly increased the expression of cupB2, cupC2, rocS1 and rocS2 in the pvcA mutant. Our results suggest that pvc influences P. aeruginosa biofilm development through the cup gene clusters in a pathway that involves paerucumarin, PtxR, and different cup regulators.

SUBMITTER: Qaisar U

PROVIDER: S-EPMC3639982 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BACKGROUND: Several strain-specific Klebsiella pneumoniae virulence determinants have been described, though these have almost exclusively been linked with hypervirulent liver abscess-associated strains. Through PCR interrogation of integration hotspots, chromosome walking, island-tagging and fosmid-based marker rescue we captured and sequenced KpGI-5, a novel genomic island integrated into the met56 tRNA gene of K. pneumoniae KR116, a bloodstream isolate from a patient with pneumonia and neutropenic sepsis. RESULTS: The 14.0 kb KpGI-5 island exhibited a genome-anomalous G +? content, possessed near-perfect 46 bp direct repeats, encoded a ?1-chaperone/usher fimbrial cluster (fim2) and harboured seven other predicted genes of unknown function. Transcriptional analysis demonstrated expression of three fim2 genes, and suggested that the fim2A-fim2K cluster comprised an operon. As fimbrial systems are frequently implicated in pathogenesis, we examined the role of fim2 by analysing KR2107, a streptomycin-resistant derivative of KR116, and three isogenic mutants (?fim, ?fim2 and ?fim?fim2) using biofilm assays, human cell adhesion assays and pair-wise competition-based murine models of intestinal colonization, lung infection and ascending urinary tract infection. Although no statistically significant role for fim2 was demonstrable, liver and kidney CFU counts for lung and urinary tract infection models, respectively, hinted at an ordered gradation of virulence: KR2107 (most virulent), KR2107?fim2, KR2107?fim and KR2107?fim?fim2 (least virulent). Thus, despite lack of statistical evidence there was a suggestion that fim and fim2 contribute additively to virulence in these murine infection models. However, further studies would be necessary to substantiate this hypothesis. CONCLUSION: Although fim2 was present in 13% of Klebsiella spp. strains investigated, no obvious in vitro or in vivo role for the locus was identified, although there were subtle hints of involvement in urovirulence and bacterial dissemination from the respiratory tract. Based on our findings and on parallels with other fimbrial systems, we propose that fim2 has the potential to contribute beneficially to pathogenesis and/or environmental persistence of Klebsiella strains, at least under specific yet-to-be identified conditions.

Project description:Hfq is an RNA chaperone that serves as a master regulator of bacterial physiology. Here we show that in the opportunistic pathogen Pseudomonas aeruginosa, the loss of Hfq can result in a dramatic reduction in growth in a manner that is dependent upon MexT, a transcription regulator that governs antibiotic resistance in this organism. Using a combination of chromatin immunoprecipitation with high-throughput sequencing and transposon insertion sequencing, we identify the MexT-activated genes responsible for mediating the growth defect of hfq mutant cells. These include a newly identified MexT-controlled gene that we call hilR We demonstrate that hilR encodes a small protein that is acutely toxic to wild-type cells when produced ectopically. Furthermore, we show that hilR expression is negatively regulated by Hfq, offering a possible explanation for the growth defect of hfq mutant cells. Finally, we present evidence that the expression of MexT-activated genes is dependent upon GshA, an enzyme involved in the synthesis of glutathione. Our findings suggest that Hfq can influence the growth of P. aeruginosa by limiting the toxic effects of specific MexT-regulated genes. Moreover, our results identify glutathione to be a factor important for the in vivo activity of MexT.IMPORTANCE Here we show that the conserved RNA chaperone Hfq is important for the growth of the opportunistic pathogen Pseudomonas aeruginosa We found that the growth defect of hfq mutant cells is dependent upon the expression of genes that are under the control of the transcription regulator MexT. These include a gene that we refer to as hilR, which we show is negatively regulated by Hfq and encodes a small protein that can be toxic when ectopically produced in wild-type cells. Thus, Hfq can influence the growth of P. aeruginosa by limiting the toxic effects of MexT-regulated genes, including one encoding a previously unrecognized small protein. We also show that MexT activity depends on an enzyme that synthesizes glutathione.

Project description:BACKGROUND: The global spread of bacterial resistance has given rise to a growing interest in new anti-bacterial agents with a new strategy of action. Pilicides are derivatives of ring-fused 2-pyridones which block the formation of the pili/fimbriae crucial to bacterial pathogenesis. They impair by means of a chaperone-usher pathway conserved in the Gram-negative bacteria of adhesive structures biogenesis. Pili/fimbriae of this type belong to two subfamilies, FGS and FGL, which differ in the details of their assembly mechanism. The data published to date have shown that pilicides inhibit biogenesis of type 1 and P pili of the FGS type which are encoded by uropathogenic E. coli strains. RESULTS: We evaluated the anti-bacterial activity of literature pilicides as blockers of the assembly of a model example of FGL-type adhesive structures--the Dr fimbriae encoded by a dra gene cluster of uropathogenic Escherichia coli strains. In comparison to the strain grown without pilicide, the Dr? bacteria cultivated in the presence of the 3.5 mM concentration of pilicides resulted in a reduction of 75 to 87% in the adherence properties to CHO cells expressing Dr fimbrial DAF receptor protein. Using quantitative assays, we determined the amount of Dr fimbriae in the bacteria cultivated in the presence of 3.5 mM of pilicides to be reduced by 75 to 81%. The inhibition effect of pilicides is concentration dependent, which is a crucial property for their use as potential anti-bacterial agents. The data presented in this article indicate that pilicides in mM concentration effectively inhibit the adherence of Dr? bacteria to the host cells--the crucial, initial step in bacterial pathogenesis. CONCLUSIONS: Structural analysis of the DraB chaperone clearly showed it to be a model of the FGL subfamily of chaperones. This permits us to conclude that analyzed pilicides in mM concentration are effective inhibitors of the assembly of adhesins belonging to the Dr family, and more speculatively, of other FGL-type adhesive organelles. The presented data and those published so far permit to speculate that based on the conservation of chaperone-usher pathway in Gram-negative bacteria , the pilicides are potential anti-bacterial agents with activity against numerous pathogens, the virulence of which is dependent on the adhesive structures of the chaperone-usher type.

Dataset Information

The pvc operon regulates the expression of the Pseudomonas aeruginosa fimbrial chaperone/usher pathway (cup) genes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets