Project description:Posttranscriptional regulator RsmA is part of a regulatory system that controls production of plant cell wall degrading enzymes (PCWDEs), motility and other virulence factors among the Pectobacterium spp of plant pathogens. We constructed the knockout mutation of rsmA gene in Pectobacterium wasabiae strain SCC3193. The rsmA- strain has three times lower growth rate but increased virulence when compared to wild type. To explain this phenotype we compared wild type and rsmA- mRNA levels using genome wide microarray. We found that the synthesis of all known virulence factors and flagella is upregulated, while cell division and peptidoglycan synthesis is down regulated in rsmA- strain. The TCA cycle is directed fully to energy production, indicating low energetic status of the cell that is a probable reason for the low growth rate of the mutant. Growth experiments showed that the enzymatic activities of extracellular virulence factors polygalacturonase and pectate lyase are very high throughout the growth curve even without induction by plant component. Wild type cells are rod shaped in liquid media, but elongated and hyperflagellated in swarm plate containing potato tuber extract and in potato tuber. The rsmA- strain exhibits the same conditional phenotype, but differentiation into swarmer cells is faster and cell elongation more pronounced. Virulence experiments in potato tuber showed that although rsmA- strain causes bigger tissue maceration, its ability to compete with the natural bacterial community in the host is decreased. We conclude that the lack of RsmA switches the cells to infective phenotype characterized by expression of virulence factors and swarming. The lack of control over these energy costly processes is probably the reason for decreased growth rate and fitness. Gene expression analysis from P. wasabie SCC3193 wildtype and SCC3193 rsmA mutant was performed on RNA samples extraxcted from the rsmA mutant (at 40 and 48 hours) and wildtype (at 24 hours). The strain were grown on 1.5% agar M9 minimal media plates supplemented with 10% potato extract. Three biological replicates were used from each strain at each time point.

Project description:Global expression profiling of airway epithelial cells infected with Pseudomonas aeruginosa and the rsmA mutant. Recent work in our laboratory investigated the impact of RsmA on a number of airway epithelial cell phenotypes including actin depolymerization, cytotoxicity and invasion. These cellular phenotypes were influenced by the positive effect of RsmA on the expression of the TTSS in P. aeruginosa (Mulcahy et al. 2006. Infect. Immun.). Pseudomonas aeruginosa is an important opportunistic pathogen which is capable of causing both acute and chronic infections in immunocompromised patients. Successful adaptation of the bacterium to its host environment relies on the ability of the organism to tightly regulate gene expression. RsmA, a small RNA-binding protein, controls the expression of a large number of virulence-related genes in P. aeruginosa, including those encoding the type III secretion system and associated effector proteins, with important consequences for epithelial cell morphology and cytotoxicity. In order to examine the influence of RsmA-regulated functions in the pathogen on gene expression in the host, we compared global expression profiles of airway epithelial cells in response to infection with P. aeruginosa PAO1 and an rsmA mutant. The RsmA-dependent response of host cells was characterized by significant changes in the global transcriptional pattern, including the increased expression of two Kruppel-like factors, KLF2 and KLF6. This increased expression was mediated by specific type III effector proteins. ExoS was required for the enhanced expression of KLF2, whereas both ExoS and ExoY were required for the enhanced expression of KLF6. Neither ExoT nor ExoU influenced the expression of the transcription factors. Additionally, the increased gene expression of KLF2 and KLF6 was associated with ExoS-mediated cytotoxicity. Therefore, this study identifies for the first time the human transcription factors KLF2 and KLF6 as targets of the P. aeruginosa type III exoenzymes S and Y, with potential importance in host cell death. Keywords: Expression profiling, Pseudomonas aeruginosa, microbial infection, airway epithelial cells, cystic fibrosis, exoenzymes, ExoS, ExoT, ExoU, ExoY, Kruppel-like factors, KLF2, KLF6

Project description:Global expression profiling of airway epithelial cells infected with Pseudomonas aeruginosa and the rsmA mutant. Recent work in our laboratory investigated the impact of RsmA on a number of airway epithelial cell phenotypes including actin depolymerization, cytotoxicity and invasion. These cellular phenotypes were influenced by the positive effect of RsmA on the expression of the TTSS in P. aeruginosa (Mulcahy et al. 2006. Infect. Immun.). Pseudomonas aeruginosa is an important opportunistic pathogen which is capable of causing both acute and chronic infections in immunocompromised patients. Successful adaptation of the bacterium to its host environment relies on the ability of the organism to tightly regulate gene expression. RsmA, a small RNA-binding ; protein, controls the expression of a large number of virulence-related genes in P. aeruginosa, including those encoding the type III secretion system and associated effector proteins, with important consequences for epithelial cell morphology and cytotoxicity. In order to examine the influence of RsmA-regulated functions in ; the pathogen on gene expression in the host, we compared global expression profiles of airway epithelial cells in response to infection with P. aeruginosa PAO1 and an rsmA mutant. The RsmA-dependent response of host cells was characterized by significant changes in the global transcriptional pattern, including the increased expression of two Kruppel-like factors, KLF2 and KLF6. This increased expression was mediated by specific type III effector proteins. ExoS was required for the enhanced expression of KLF2, whereas both ExoS and ExoY were required for the enhanced expression of KLF6. Neither ExoT nor ExoU influenced the expression of the transcription factors. Additionally, the increased gene expression of KLF2 and KLF6 was associated with ExoS-mediated cytotoxicity. Therefore, this study identifies for the first time the human transcription factors ; KLF2 and KLF6 as targets of the P. aeruginosa type III exoenzymes S and Y, with potential importance in host cell death. Experiment Overall Design: RNA isolation and microarray sample preparation Experiment Overall Design: Biological samples from two independent infection experiments were used in two independent microarray experiments as outlined below. Total RNA was isolated from epithelial cells using a RNeasy Kit (Qiagen) according to manufacturer's instructions. Genomic DNA was removed using DNA-free (Ambion) and confirmed by PCR to be free of DNA, prior to cDNA synthesis. Isolated RNA was used in the preparation of fragmented cRNA for microarray hybridization according to the manufacturer's protocol (Affymetrix). Briefly, 8.5ug of RNA was converted to double stranded cDNA by reverse transcription, using a Superscript cDNA synthesis kit (Invitrogen), with an oligo dT primer containing a T7 RNA polymerase site added 3' of the poly (T) (Affymetrix). After second strand synthesis, cDNA was converted to biotin-labelled cRNA by in vitro transcription (Enzo). The labelled cRNA was purified using Genechip clean up module (Qiagen). Total cRNA quality and yield was measured using a GeneQuant spectrophotometer and 20ug of cRNA was fragmented at 94ÂºC for 35 mins in fragmentation buffer (40 mM tris acetate, pH 8.1, 100 mM potassium acetate, 30 mM magnesium acetate). Full length and fragmented cRNA sample integrity was assessed by electrophoresis on a 1% agarose-TBE gel visualized by staining with SyBr green. Fragmented cRNA was sent to MRC geneservice (Cambridge, UK) for assessment of RNA quality using a Bioanalyzer (Agilent) before hybridization and scanning. The arrays were washed and stained in a fluidics station and scanned according to the manufacturer's protocols (Affymetrix). Experiment Overall Design: Microarray data analysis Experiment Overall Design: Raw image analysis was performed using Microarray Suite v5.0 software (Affymetrix). Downstream data analysis was performed using GeneSight software version 2.7 (Biodiscovery). For all analyses, the signal intensities from two independent infection and microarray experiments were used. Statistically significant changes in gene expression were identified by firstly performing analysis of variance (ANOVA), for comparison between multiple groups, with a P value of < 0.05. The list of transcripts generated using ANOVA was then subjected to a Student's t-test, for comparison between two groups, with a P value of < 0.05. To identify different levels of gene expression compared to baseline, a fold change cut-off of greater than or equal to 1.5 was applied to this data.

Dataset Information

Gene expression analysis of wild type Pectobacteriumwasabie SCC3193 wildtype compared to a SCC3193 inactivation mutant of RsmA, inactivation mutant of ExpA and an ExpA RsmA double inactivation mutant.

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets