Project description:Pseudomonas aeruginosa (Pa) is one of the main causative agents of nosocomial infections and the spread of multidrug-resistant strains is rising. The outer membrane composition of Pa restricts antibiotic entry and determines virulence. For efficient outer membrane protein biogenesis, the BAM complex and chaperones like Skp and SurA are crucial. Deletion mutants of bamB, bamC and the skp homolog hlpA as well as a conditional mutant of surA were investigated. The most profound effects were associated with a lack of SurA, characterized by increased membrane permeability, enhanced sensitivity to antibiotic treatment and attenuation of virulence in a Galleria mellonella infection model. Strikingly, the conditional deletion of surA in a multidrug-resistant bloodstream isolate re-sensitized the strain to antibiotic treatment. Mass spectrometry revealed striking alterations in the outer membrane composition. Thus, SurA of Pa is important for the insertion of many porins, type V secretion systems, TonB-dependent receptors, proteins involved in LPS transport and BAM complex components. Therefore, SurA of Pa serves as a promising target for developing a drug that shows antiinfective activity and sensitizes multidrug-resistant strains to antibiotics.
Project description:In this study, a comparative analysis was performed on two clinical Pa strains from pneumonia patients, 1) an acute strain (CMC-115) and 2) a chronic multidrug- and carbapenem-resistant strain (CMC-097), with distinct phenotypic and genetic characteristics. A transcriptome analysis using both the Pseudomonas DNA GeneChip microarray and Illumina RNA-Seq technologies was carried out for both strains at early-stationary growth phase in laboratory culture. The comparative transcriptomic analysis identified 134 genes differentially expressed ≥4.0-fold by both technologies between the two strains, which included virulence genes such as flagellar, pyoverdine, and phenazine genes, that were higher in the acute strain, CMC-115, and type 3 secretory system (T3SS) and pyochelin biosynthesis genes, that were higher in the chronic strain, CMC-097. In particular, the DNA microarrays suggested and the RNA-Seq analysis confirms the type 3 secretory system genes were completely missing from the acute strain, CMC-115. The combined analysis using the RNA-Seq and DNA microarray methods also identified important genes that were either missing or highly divergent from the Reference PAO1 genome used for the DNA microarray design. For example, the RNA-Seq data identified an operon containing several multidrug resistance genes: aacA27, beta-lactamase (blaOXA-2), qacΔE, sul1, and GNAT-N, in the chronic strain, CMC-097.
Project description:Methylrhodomelol (1) is a bromophenol from the red alga Vertebrata lanosa (L.) T.A.Christensen that has been associated with antimicrobial properties. Aim of the current study was therefore, to assess the antimicrobial potential of this compound in more detail against the gram-negative pathogen Pseudomonas aeruginosa. 1 exerted weak bacteriostatic activity against different strains when grown in minimal medium, whereas other phenolics were inactive. In addition, 1 (35 and 10 µg/mL) markedly enhanced the susceptibility of multidrug resistant P. aeruginosa towards the aminoglycoside gentamicin, while it did not affect the viability of Vero kidney cells up to 100 µM. Finally, pyoverdine release was reduced in bacteria treated at sub-inhibitory concentration, but no effect on other virulence factors was observed. Transcriptome analysis of treated versus untreated P. aeruginosa indicated an interference of 1 with bacterial carbon and energy metabolism, which was corroborated by RT-qPCR and decreased ATP-levels in treated bacteria.
Project description:We implemented transcriptional analysis methods using cDNA and high-throughput sequencing data to identify HrpL-regulated genes for six strains of Pseudomonas syringae Each Pseudomonas syringae strains was transformed with either pBAD::EV or pBAD containing native hrpL sequence. Strains were grown in MM media supplemented with arabinose and collected 1, 3, and 5 hours post arabinose treatment. RNA was extracted for each time point and mixed at a 1/3 ratio. After removal of rRNA, double stranded cDNA was generated and library prepared accordeing to Illumina protocols.
Project description:Polymyxins are the last-line antibiotics against multidrug-resistant Pseudomonas aeruginosa however, resistance to polymyxins has been increasingly reported. Therefore, understanding the mechanisms of polymyxin activity and resistance is crucial for preserving their clinical usefulness. This study employed comparative metabolomics and transcriptomics to investigate the responses of polymyxin-susceptible PAK (polymyxin B MIC 1 mg/l) and its polymyxin-resistant pmrB mutant PAKpmrB6 (MIC 16 mg/l) to polymyxin B (4, 8, and 128 mg/l) at 1, 4, and 24h. Our results revealed that polymyxin B at 4 mg/l induced different metabolic and transcriptomic responses between polymyxin-susceptible and -resistant P. aeruginosa. In PAK, polymyxin B significantly activated PmrAB and the mediated arn operon, leading to increased 4-amino-4-deoxy-L-arabinose (L-Ara4N) synthesis and the addition to lipid A. On the contrary, polymyxin B did not increase lipid A modification in PAKpmrB6. Moreover, the syntheses of lipopolysaccharide and peptidoglycan were significantly decreased in PAK, but increased in PAKpmrB6 due to polymyxin B treatment. In addition, 4 mg/l polymyxin B significantly perturbed phospholipid and fatty acid levels and induced oxidative stress in PAK, but not in PAKpmrB6. Notably, the increased trehalose-6-phosphate levels indicate that polymyxin B potentially caused osmotic imbalance in both strains. Furthermore, 8 and 128 mg/l polymyxin B significantly elevated lipoamino acid levels and decreased phospholipid levels, but without dramatic changes in lipid A modification in both wildtype and mutant strains. Overall, this systems study is the first to elucidate the complex and dynamic interactions of multiple cellular pathways associated with polymyxin mode of action against P. aeruginosa.