Project description:Pseudomonas aeruginosa airway infection is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients. In vitro models that closely mimic CF sputum are needed to improve understanding of the pathobiology of P. aeruginosa in the CF airway. We developed an artificial sputum medium (ASMDM) that more closely resembles the composition of CF sputum than current media. In order to validate the utility of ASMDM, we used GeneChip microarrays to compare expression data of P. aeruginosa UCBPP-PA14 (PA14) in ASMDM with published data for this strain grown under the same conditions in an artificial medium containing 10% (v/v) CF sputum. Thirty-seven of 39 nutrition-related genes were differentially expressed in the same manner in both media. However, 24 quorum-sensing (QS) genes, 23 Type III secretion system and several anaerobic respiration genes were more highly expressed in ASMDM than in sputum-containing medium. When grown to stationary phase in ASMDM, PA14 differentially expressed about 50 biologically significant genes compared to stationary phase growth in Luria Broth; genes involved in iron acquisition (pfeA, fepC) and in assimilatory nitrate reduction (nasC, nirD) were upregulated, while 24 QS genes, including the regulator rhlR, lasA, rsaL, aprADEI and phenazine genes phzC2DD2EG2 were downregulated. Downregulation of QS-regulated virulence genes has been noted in chronic P. aeruginosa infection. ASMDM thus appears highly suitable for studies on gene expression of (i) P. aeruginosa strains from acutely and chronically infected CF patients and (ii) established biofilms that are a hallmark of advanced CF lung disease.
Project description:Pseudomonas aeruginosa airway infection is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients. In vitro models that closely mimic CF sputum are needed to improve understanding of the pathobiology of P. aeruginosa in the CF airway. We developed an artificial sputum medium (ASMDM) that more closely resembles the composition of CF sputum than current media. In order to validate the utility of ASMDM, we used GeneChip microarrays to compare expression data of P. aeruginosa UCBPP-PA14 (PA14) in ASMDM with published data for this strain grown under the same conditions in an artificial medium containing 10% (v/v) CF sputum. Thirty-seven of 39 nutrition-related genes were differentially expressed in the same manner in both media. However, 24 quorum-sensing (QS) genes, 23 Type III secretion system and several anaerobic respiration genes were more highly expressed in ASMDM than in sputum-containing medium. When grown to stationary phase in ASMDM, PA14 differentially expressed about 50 biologically significant genes compared to stationary phase growth in Luria Broth; genes involved in iron acquisition (pfeA, fepC) and in assimilatory nitrate reduction (nasC, nirD) were upregulated, while 24 QS genes, including the regulator rhlR, lasA, rsaL, aprADEI and phenazine genes phzC2DD2EG2 were downregulated. Downregulation of QS-regulated virulence genes has been noted in chronic P. aeruginosa infection. ASMDM thus appears highly suitable for studies on gene expression of (i) P. aeruginosa strains from acutely and chronically infected CF patients and (ii) established biofilms that are a hallmark of advanced CF lung disease. PA14 was grown in four different ways: 1. Logarithmic growth for early gene expression Cells were grown in MOPS-Glucose and separately in ASMDM. The average of two biological duplicates in each case was compared to the other to determine differential gene expression. 2. Stationary phase growth for gene expression Cells were grown in Luria Broth and separately in ASMDM. The average of two biological duplicates in each case was compared to the other to determine differential gene expression.
Project description:Comparative transcriptome analyses of P. aeruginosa PA14 pyrF mutant with PA14 wild type, and with PA14 pyrF mutant with 1 mM uracil supplement and PA14 wild type with 10 mM uracil in biofilm cells. All samples were cultured in LB with glass wool at 37C for 7h. Keywords: Pseudomonas aeruginosa biofilm pyrF uracil
Project description:The Pseudomonas aeruginosa MvfR-dependent QS regulatory pathway controls the expression of key virulence genes; and is activated via the extracellular signals 4-hydroxy-2-heptylquinoline (HHQ) and 3,4-dihydroxy-2-heptylquinoline (PQS). Our findings reveal a multi-layered homeostatic regulation of PQS and HHQ and the MvfR regulon component PqsE which is a key mediator in orchestrating this homeostatic regulation.
Project description:P. aeruginosa PA14 mutant strain PA4496 expression in biofilm cells relative to PA14 wild-type strain expression in biofilm cells. All samples cultured in LB with glass wool
Project description:The Pseudomonas aeruginosa MvfR-dependent QS regulatory pathway controls the expression of key virulence genes; and is activated via the extracellular signals 4-hydroxy-2-heptylquinoline (HHQ) and 3,4-dihydroxy-2-heptylquinoline (PQS), whose syntheses depend on anthranilic acid (AA), the primary precursor of 4-hydroxy-2-alkylquinolines (HAQs). We identified halogenated AA analogs that specifically inhibited HAQ biosynthesis and disrupted MvfR-dependent gene expression. These compounds restricted P. aeruginosa systemic dissemination and mortality in mice, without perturbing bacterial viability, and inhibited osmoprotection, a widespread bacterial function.