Unknown,Transcriptomics,Genomics,Proteomics

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Protoanemonin: A new natural quorum sensing inhibitor that selectively activates iron starvation response

ABSTRACT: Many Gram-negative bacteria employ cell-to-cell communication mediated by N-acyl homoserine lactones (quorum sensing) to control expression of a wide range of genes including, but not limited to, genes encoding virulence factors. Outside the laboratory, the bacteria live in complex communities where signals may be perceived across species. We here present a newly found natural quorum sensing inhibitor, produced by the pseudomonads Pseudomonas sp. B13 and Pseudomonas reinekei MT1 as a blind end in the biodegradation of organochloride xenobiotics, which inhibits quorum sensing in P.M-bM-^@M-^Caeruginosa in naturally occurring concentrations. This catabolite, 4-methylenebut-2-en-4-olide, also known as protoanemonin, has been reported to possess antibacterial properties, but seems to have dual functions. Using transcriptomics and proteomics, we found that protoanemonin significantly reduced expression of genes and secretion of proteins known to be under control of quorum sensing in P.M-bM-^@M-^Caeruginosa. Moreover, we found activation of genes and gene products involved in iron starvation response. It is thus likely that inhibition of quorum sensing, as the production of antibiotics, is a phenomenon found in complex bacterial communities. Strain P. aeruginosa MPAO1 was cultivated under defined ABT medium. The orginal culture was divided in the early exponential phase into two parts. One was treated with 125M-NM-

ORGANISM(S): Pseudomonas aeruginosa

SUBMITTER: Piotr Bielecki

PROVIDER: E-GEOD-27674 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Protoanemonin: a natural quorum sensing inhibitor that selectively activates iron starvation response.

Bobadilla Fazzini Roberto A RA Skindersoe Mette E ME Bielecki Piotr P Puchałka Jacek J Givskov Michael M Martins sos Santos Vitor A P VA

Environmental microbiology 20120605 1

Many Gram-negative bacteria employ cell-to-cell communication mediated by N-acyl homoserine lactones (quorum sensing) to control expression of a wide range of genes including, but not limited to, genes encoding virulence factors. Outside the laboratory, the bacteria live in complex communities where signals may be perceived across species. We here present a newly found natural quorum sensing inhibitor, produced by the pseudomonads Pseudomonas sp. B13 and Pseudomonas reinekei MT1 as a blind end i ...[more]

PMID: 22672701

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Project description:Background Small colony variants (SCVs) are slow-growing bacteria, which often show increased resistance to antibiotics and cause latent or recurrent infections. It is therefore important to understand the mechanisms at the basis of this phenotypic switch. Methodology/Principal findings One SCV (termed PAO-SCV) was isolated, showing high resistance to gentamicin and to the cephalosporine cefotaxime. PAO-SCV was prone to reversion as evidenced by emergence of large colonies with a frequency of 10-5 on media without antibiotics while it was stably maintained in presence of gentamicin. PAO-SCV showed a delayed growth, defective motility, and strongly reduced levels of the quorum sensing Pseudomonas quinolone signal (PQS). Whole genome expression analysis further suggested a multi-layered antibiotic resistance mechanism, including simultaneous over-expression of two drug efflux pumps (MexAB-OprM, MexXY-OprM), the LPS modification operon arnBCADTEF, and the PhoP-PhoQ two-component system. Conversely, the genes for the synthesis of PQS were strongly down-regulated in PAOSCV. Finally, genomic analysis revealed the presence of mutations in phoP and phoQ genes as well as in the mexZ gene encoding a repressor of the mexXY and mexABoprM genes. Only one mutation occurred only in REV, at nucleotide 1020 of the tufA gene, a paralog of tufB, both encoding the elongation factor Tu, causing a change of the rarely used aspartic acid codon GAU to the more common GAC, possibly causing an increase of tufA mRNA translation. High expression of phoP and phoQ was confirmed for the SCV variant while the revertant showed expression levels reduced to wild-type levels. Conclusions By combining data coming from phenotypic, gene expression and proteome analysis, we could demonstrate that resistance to aminoglycosides in one SCV mutant is multifactorial including overexpression of efflux mechanisms, LPS modification and is accompanied by a drastic down-regulation of the Pseudomonas quinolone signal quorum sensing system. We used microarrays to study changes in gene expression during early and late stationary phase of SCV and WT strains. SCV and WT cultures were grown in triplicate until early (24h) and late (48h) stationary phase. RNA was extracted, labelled and hybridised on Affymetrix P. aeruginosa expression microarrays.

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Protoanemonin: A new natural quorum sensing inhibitor that selectively activates iron starvation response

Publications

Protoanemonin: a natural quorum sensing inhibitor that selectively activates iron starvation response.

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