Project description:An experiment to identify the downstream targets of PatE, a prophage encoded AraC-like transcriptional regulator, in transcriptional activation of acid-resistance pathways of enterohemorrhagic Escherichia coli strain EDL933 using deletion and complementation strains (Delta3 and Delta3_1, respectively).
Project description:An experiment to identify the downstream targets of PatE, a prophage encoded AraC-like transcriptional regulator, in transcriptional activation of acid-resistance pathways of enterohemorrhagic Escherichia coli strain EDL933 using deletion and complementation strains (Delta3 and Delta3_1, respectively). Incomplete 2 factor with dye swaps. Genotype: 3 levels (wt, detla3, delta3_1) Bicarbonate: 2 levels (pos, neg) on wt only. 4 biological replicates, 2 in each dye orientation. Microarrays processed at Australian Genome Research Facility.
Project description:The microarray study was used to compare the gene expression profile of EDL933 in LB, sdhA deletion mutant in LB, and sdhA deletion mutant in LB with 2.5 mM Fumaric acid.
Project description:RpoS is a conserved stress regulator that plays a critical role in survival under stress conditions in Escherichia coli and other γ-proteobacteria. RpoS is also involved in virulence of many pathogens including Salmonella and Vibrio species. Though well characterized in non-pathogenic E. coli K12 strains, the effect of RpoS on transcriptome expression has not been examined in pathogenic isolates. E. coli O157:H7 is a serious human enteropathogen, possessing a genome 20% larger than that of E. coli K12, and many of the additional genes are required for virulence. The genomic difference may result in substantial changes in RpoS-regulated gene expression. To test this, we compared the transcriptional profile of wild type and rpoS mutants of the E. coli O157:H7 EDL933 type strain. The rpoS mutation had a pronounced effect on gene expression in stationary phase, and more than 1,000 genes were differentially expressed (two-fold, p<0.05). By contrast, we found 11 genes expressed differently in exponential phase. Western blot analysis revealed that, as expected, RpoS level was low in exponential phase and substantially increased in stationary phase. The defect in rpoS resulted in impaired expression of genes responsible for stress response (e.g., gadA, katE and osmY), arginine degradation (astCADBE), putrescine degradation (puuABCD), fatty acid oxidation (fadBA and fadE), and virulence (ler, espI and cesF). For EDL933-specific genes on O-islands, we found 50 genes expressed higher in wild type EDL933 and 49 genes expressed higher in the rpoS mutants. The protein levels of Tir and EspA, two LEE-encoded virulence factors, were elevated in the rpoS mutants under LEE induction conditions. Our results show that RpoS has a profound effect on global gene expression in the pathogenic strain O157:H7 EDL933, and the identified RpoS regulon, including many EDL933-specific genes, differs substantially from that of laboratory K12 strains. In this study, we characterized the RpoS regulon of E. coli O157:H7 strain EDL933 using microarray analysis.
Project description:In order to define the role of H-NS in regulating gene transcription and further find out the biological significance of this protein in EHEC, we conducted RNA-seq and then analyzed the transcriptome data, using EHEC O157:H7 strain EDL933 and Δhns. A total of 983 genes were found to be regulated by H-NS. 213 and 770 genes exhibited lower and higher transcript levels in Δhns than in WT, respectively. For instance, chemotaxis and flagellar associated genes were down-regulated in Δhns. Besides, 34 genes on virulence plasmid pO157 were down-regulated by H-NS. The outcome of RNA-seq were verified by real time quantitative PCR. As reported in Salmonella Typhimurium, Δhns showed a growth deficiency and altered fitness. We first detected that both stx1 and stx2 in EDL933 were repressed by H-NS. Although no survival difference between EDL933 and Δhns was detected when phagocytized by macrophage, we characterized the higher ability of colonization and in consequence the higher virulence of Δhns to BALB/c mice by experimental analyses than those of WT, especially when intact commensal flora of mice existed. This might indeed help us understand the core role of H-NS in depth.
