Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E104. In this strain, RhlR positively regulates 48 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E167. In this strain, RhlR positively regulates 78 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E131. In this strain, RhlR positively regulates 105 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E125. In this strain, RhlR positively regulates 28 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
Project description:In people with the genetic disease cystic fibrosis (CF), bacterial infections involving the opportunistic pathogen Pseudomonas aeruginosa are a significant cause of morbidity and mortality. P. aeruginosa uses a cell-cell signaling mechanism called quorum sensing (QS) to regulate many virulence functions. One type of QS consists of acyl-homoserine lactone (AHL) signals produced by LuxI-type signal synthases, which bind a cognate LuxR-type transcription factor. In laboratory strains and conditions, P. aeruginosa employs two AHL synthase/receptor pairs arranged in a hierarchy, with the LasI/R system controlling the RhlI/R system and many downstream virulence factors. However, P. aeruginosa isolates with inactivating mutations in lasR are frequently isolated from chronic CF infections. We and others have shown that these isolates frequently use RhlR as the primary QS regulator. RhlR is rarely mutated in CF and environmental settings. We were interested if there were reproducible genetic characteristics of these isolates and if there was a central group of genes regulated by RhlR in all isolates. We examined five isolates and found signatures of adaptation common to CF isolates. Here, we analyzed CF clinial isolate E113. In this strain, RhlR positively regulates 186 genes, including those coding for known virulence factors. These results suggest a key group of QS-regulated factors important for pathogenesis of chronic infection, and position RhlR as a target for anti-QS therapeutics. Our work underscores the need to sample a diversity of isolates to understanding QS beyond what has been described in laboratory strains.
Project description:Gene expression profiles of two Pseudomonas aeruginosa taxonomic outlier clinical isolates, CLJ1 and CLJ3 [CLJ3] Pseudomonas aeruginosa taxonomic outliers emerged recently as infectious for humans, provoking hemorrhagic pneumonia. Those bacteria lack classical type III secretion system, and utilize the pore-forming toxin for infection. Two clones CLJ1 and CLJ3 belonging to these taxonomic outliers have been isolated from the same patient at two different times during hospitalization. P. aeruginosa CLJ3 displays antibiotic resistance phenotype, while CLJ1 is more cytotoxic on epithelial and endothelial cells.
Project description:Gene expression profiles of two Pseudomonas aeruginosa taxonomic outlier clinical isolates, CLJ1 and CLJ3 [CLJ1] Pseudomonas aeruginosa taxonomic outliers emerged recently as infectious for humans, provoking hemorrhagic pneumonia. Those bacteria lack classical type III secretion system, and utilize the pore-forming toxin for infection. Two clones CLJ1 and CLJ3 belonging to these taxonomic outliers have been isolated from the same patient at two different times during hospitalization. P. aeruginosa CLJ3 displays antibiotic resistance phenotype, while CLJ1 is more cytotoxic on epithelial and endothelial cells.
Project description:Pseudomonas aeruginosa (P. aeruginosa) lung infection is a significant cause of mortality in patients with cystic fibrosis (CF). Most CF patients acquire unique P. aeruginosa strains from the environment; however clonal strains have been identified in CF communities in several countries. Two clonal strains infect 10% to 40% of patients in three CF clinics in mainland eastern Australia. The expression profiles of four planktonically-grown isolates of one Australian clonal strain (AES-2), and four non–clonal CF P. aeruginosa isolates were compared to each other and to the reference strain PAO1 using the Affymetrix P. aeruginosa PAO1 genome array, to gain insight into properties mediating the enhanced infectivity of AES-1. The isolates were subsequently grown as 3-day old biofilms and similarly extracted for RNA and compared as above. Data analysis was carried out using BIOCONDUCTOR software. Keywords: Comparative strain hybridization
Project description:Pseudomonas aeruginosa (P. aeruginosa) lung infection is a significant cause of mortality in patients with cystic fibrosis (CF). Most CF patients acquire unique P. aeruginosa strains from the environment; however clonal strains have been identified in CF communities in several countries. Two clonal strains infect 10% to 40% of patients in three CF clinics in mainland eastern Australia. The expression profiles of four planktonically-grown isolates of one Australian clonal strain (AES-1), and four non–clonal CF P. aeruginosa isolates were compared to each other and to the reference strain PAO1 using the Affymetrix P. aeruginosa PAO1 genome array, to gain insight into properties mediating the enhanced infectivity of AES-1. The isolates were subsequently grown as 3-day old biofilms and similarly extracted for RNA and compared as above. Data analysis was carried out using BIOCONDUCTOR software. Keywords: Comparative strain hybridization