Project description:Sigma factors are master regulators of bacterial transcription which direct gene expression of specific subsets of genes. In particular, alternative sigma factors are well-known to be key players of bacterial adaptation to changing environments. To elucidate the regulatory network of sigma factors in P. aeruginosa, an integrative approach including ChIP-seq of 11 polyhistidine-tag sigma factors was performed to define the primary regulon of each sigma factor.
Project description:Staphylococcus aureus and Pseudomonas aeruginosa are bacterial pathogens that have been shown to co-exist in biofilms related to numerous infections. Although the interaction between these two species is competitive, both partially benefit from the coexistence. In this study, we exhaustively characterized the interaction between Staphylococcus aureus and Pseudomonas aeruginosa by utilizing a proteomics approach, individually targeting the surface-associated proteins (surfaceome), and proteins secreted or otherwise liberated to the extracellular space (exoproteome). To that end, the conditions to co-culture S. aureus and P. aeruginosa in vitro were optimized and a high-resolution proteomics approach was applied to compare surface-associated and extracellular protein profiles between mono- and co-cultured biofilms.
Project description:Untargeted metabolomics analysis of in vitro headspace volatiles from 81 Pseudomonas aeruginosa bacterial isolates from individuals with cystic fibrosis. Headspace volatiles were collected using solid-phase microextraction (SPME) (in triplicate) and comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GCxGC-TOFMS). 15 replicates of un-inoculated media were prepared and analyzed in parallel, for a total of 258 samples.
Project description:P. aeruginosa is known to cause acute cytotoxicity against various human and animal cells and tissues. We identified bacterial metabolite - phenylacetic acid (PAA) which acts as an inhibitory molecule counteracting its pathogenic infection. Microarray and genetic analyses were conducted to investigate the inhibitory mechanism of the identified inhibitor PAA on bacterial virulence. Microarray analysis revealed that treatment of P. aeruginosa with PAA down-regulated the transcriptional expression of type 3 secretion systems (T3SS) genes and related regulatory genes including rsmA and vfr, which were confirmed by transcriptional and translational analysis. Our findings present a new insight to the puzzle of high-cell-density-modulated virulence attenuation in P. aeruginosa and the regulatory mechanisms of T3SS which is associated with bacterial acute infection. Overnight PAO1 culture were diluted 1:200 to fresh LB medium supplemented with nitriloacetic acid (NTA) with or without addition of 1 mM of phenylacetic acid (PAA). The growth was continued with shaking at 37M-BM-0C for 4 h to allow OD600 reaching about 1.5 and the cells were used for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Sigma factors are master regulators of bacterial transcription which direct gene expression of specific subsets of genes. In particular, alternative sigma factors are well-known to be key players of bacterial adaptation to changing environments. To elucidate the regulatory network of sigma factors in P. aeruginosa, an integrative approach including ChIP-seq of 11 polyhistidine-tag sigma factors was performed to define the primary regulon of each sigma factor. Sigma factor genes were fused to a polyhistidine-tag and provided in trans. Under optimal conditions regarding sigma factor activity and induction of sigma factor expression, DNA-sigma factor interactions were conserved by formaldehyde treatment. Upon DNA fragmentation by sonication, the complexes were specifically immunoprecipitated by polyclonal anti-6X His-tag antibodies and the purified DNA was analyzed by Illumina sequencing. DNA enrichment to a control strain was calculated and used for peak calling within promoter region (-500,+100) to identify directly regulated genes/operons.
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.
Project description:Transcriptional profiles of Escherichia coli MG1655 in mixed culture with Pseudomonas aeruginosa PAO1 showed a number of E. coli genes to be upregulated including purA-F and other genes associated with purine synthesis. In contrast, genes associated with pyrimidine synthesis were unaffected. Competition experiments in both planktonic and biofilm cultures, using three purine synthesis mutants, purD, purH, and purT showed little difference in E. coli survival from the parent strain. As purines are components of the cell signals, cAMP and c-di-GMP, we conducted competition experiments with E. coli mutants lacking adenylate cyclase (cyaA), cAMP phosphodiesterase (cpdA), and the catabolite receptor protein (crp), as well as ydeH, an uncharacterized gene that has been associated with c-di-GMP synthesis. Survival of the cyaA and crp mutants during co-culture were significantly less than the parent strain. Supplementation of the media with 1mM cAMP could restore survival of the cyaA mutant but not the crp mutant. In contrast, survival of the cpdA mutant was similar to the parent strain. Survival of the ydeH mutant was moderately less than the parent, suggesting that cAMP has more impact on E. coli mixed culture growth than c-di-GMP. Addition of 1 mM indole restored the survival of both the cyaA and crp mutations. Mutants in genes for tryptophan synthesis (trpE) and indole production (tnaA) showed a loss of competition and recovery through indole supplementation, comparable to the cyaA and crp mutants. Overall, these results suggest indole and cAMP as major contributing factors to E. coli growth in mixed culture.
Project description:Application of 200 µA of direct current to bacterial biofilms leads to cellular death. We hypothesize that bacterial death is caused, in part, by the generation of reactive oxygen species. We used microarray analysis to determine the effects at a cellular level following 60 minutes of exposure of bacterial biofilms to 200 µA direct current.
Project description:We investigated the specific interactions of the most dominant bacterial CF-pathogen, Pseudomonas aeruginosa, and the anaerobic bacterium Veilllonella parvula, that has been recovered at comparable cell numbers in the respiratory tract of CF patients. We used our recently established in-vivo murine tumor model to investigate mutual influences of the two pathogens during a biofilm-associated infection process. We found that although P. aeruginosa and V. parvula colonized distinct niches within the tumor, in mice that were co-infected with both bacterial species significant higher cell numbers of P. aeruginosa were recovered from the tumor tissue. Concordantly, in vivo transcriptional profiling implied that the presence of V. parvula supports P. aeruginosa growth at the infected host site, and the higher P. aeruginosa load correlated with clinical deterioration. We cultivated P. aeruginosa PA14 and V. parvula DSM No.:2008 in mono- and co-cultures in vivo using an established murine tumor model. Corresponding in vitro samples were generated under anaerobe growth conditions.