Project description:To explore what important role of PhoPQ TCS plays in Shigella virulence, the Agilent microarray technologies was used to compare the transcriptional profiles of Shigella flexneri 2a 301 and △phoPQ mutant strains at middle-log phase (6 h) or early-stationary phase (10 h) under LB growth conditions.
Project description:In this study, we probed factors that could influence Shigella pathogenesis. We show that in basic pH conditions, deoxycholate-induced biofilm formation and virulence of Shigella are attenuated. We utilized RNA-sequencing to investigate pathways enriched in bacterial cells in biofilms.
Project description:In this study, we analyzed the expression profiles of a virulence plasmid-cured strain and wild-type strain of shigella flexneri. The results showed that the genes of glp regulon were upregulated in mutant bacteria in stationary phase cultures.
Project description:Background Compelling evidence indicates that Shigella species, the etiologic agents of bacillary dysentery, as well as enteroinvasive Escherichia coli, are derived from multiple origins of Escherichia coli and form a single pathovar. To further understand the genome diversity and virulence evolution of Shigella, comparative genomic hybridization microarray analysis was employed to compare the gene content of E. coli K-12 with those of 43 Shigella strains from all serotypes. Results For the 43 strains subjected to CGH microarray analyses, the common backbone of the Shigella genome was estimated to contain more than 1,900 open reading frames, with a mean number of 729 undetectable ORFs. The mosaic distribution of absent regions indicated that insertions and/or deletions have led to the highly diversified genomes of pathogenic strains. Conclusion These results support the hypothesis that by gain and loss of functions, Shigella species became successful human pathogens through convergent evolution from diverse genomic backgrounds. Moreover, we also found many specific differences between different lineages, providing a window into understanding bacterial speciation and taxonomic relationships. Keywords: comparative genomic hybridization
Project description:In this study, we analyzed the expression profiles of a virulence plasmid-cured strain and wild-type strain of shigella flexneri. The results showed that the genes of glp regulon were upregulated in mutant bacteria in stationary phase cultures. The two strains were cultured in LB broth into log-phase and stationary phase respectively. Then, the total RNAs were extracted and analyzed by Nimblegen biochips.
Project description:Small regulatory RNAs (sRNAs) of Shigella dysenteriae and other pathogens are vital for the regulation of virulence-associated genes and processes. Here, we characterize RyfA1, one member of a sibling pair of sRNAs produced by S. dysenteriae. Unlike its nearly identical sibling molecule RyfA2, predicted to be encoded almost exclusively by non-pathogenic species, the presence of a gene encoding RyfA1, or a RyfA1-like molecule, is strongly correlated with virulence in a variety of enteropathogens. In S. dysenteriae, the over production of RyfA1 negatively impacts the virulence-associated process of cell-to-cell spread and the expression of ompC, a gene encoding a major outer membrane protein important for the pathogenesis of Shigella. Interestingly, the production of RyfA1 is controlled by a second sRNA, here termed RyfB1; the first incidence of one regulatory small RNA controlling another in S. dysenteriae or any Shigella species.
Project description:Trained immunity is a long-term memory of innate immune cells, generating an improved response upon re-infection. Shigella is an important human pathogen and inflammatory paradigm for which there is no effective vaccine. Using zebrafish larvae we demonstrate that after Shigella priming neutrophils are more efficient at bacterial clearance. We observe that Shigella-induced protection is non-specific and long-lasting, and is unlike training by BCG and β-glucan. Analysis of histone ChIP-seq on primed neutrophils revealed that Shigella training deposits the active H3K4me3 mark on promoter regions of 1612 genes, significantly changing the epigenetic landscape of neutrophils towards enhanced microbial recognition and mitochondrial ROS production. Finally, we demonstrate that mitochondrial ROS plays a key role in enhanced antimicrobial activity of trained neutrophils. It is envisioned that signals and mechanisms we discover here can be used in other vertebrates, including humans, to suggest new therapeutic strategies involving neutrophils to control bacterial infection.
Project description:Erwinia carotovora subsp. atroseptica (Eca) is an enterobacterial phytopathogen causing economically-significant soft rot disease. Pathogenesis is mediated by multiple secreted virulence factors, many of which are secreted by the Type II (Out) secretion system. DsbA catalyses the introduction of disulphide bonds into periplasmic and secreted proteins. In this study, the extracellular proteome (secretome) of wild type Eca SCRI1043 and dsbA and out mutants was analysed by spectral counting mass spectrometry. This revealed that dsbA inactivation had a huge impact on the secretome and identified diverse DsbA- and Out-dependent secreted proteins, representing known, predicted and novel candidate virulence factors. Further characterisation of the dsbA mutant showed that secreted enzyme activities, motility, production of the quorum sensing signal and virulence were absent or greatly reduced. The impact of DsbA on secreted virulence factor production was mediated at multiple levels, including impacting on the Out secretion system and the virulence gene regulatory network. Transcriptome analyses revealed that the abundance of a broad, but defined, set of transcripts, including many virulence factors, was altered in the dsbA mutant, identifying a new virulence regulon responsive to extracytoplasmic conditions. In conclusion, DsbA plays a crucial, multi-faceted role in the pathogenesis of Eca. Keywords: Mutant comparison RNA samples used for genome-wide transcriptional profiling using microarrays: RNA was hybridised to four Eca genomic arrays, with each array hybridising one wild type and one dsbA mutant sample (from four independent cultures of each strain) and incorporating a dye-swap (i.e. wild type labelled with Cy3 in 2/4 and with Cy5 in 2/4).
Project description:Erwinia carotovora subsp. atroseptica (Eca) is an enterobacterial phytopathogen causing economically-significant soft rot disease. Pathogenesis is mediated by multiple secreted virulence factors, many of which are secreted by the Type II (Out) secretion system. DsbA catalyses the introduction of disulphide bonds into periplasmic and secreted proteins. In this study, the extracellular proteome (secretome) of wild type Eca SCRI1043 and dsbA and out mutants was analysed by spectral counting mass spectrometry. This revealed that dsbA inactivation had a huge impact on the secretome and identified diverse DsbA- and Out-dependent secreted proteins, representing known, predicted and novel candidate virulence factors. Further characterisation of the dsbA mutant showed that secreted enzyme activities, motility, production of the quorum sensing signal and virulence were absent or greatly reduced. The impact of DsbA on secreted virulence factor production was mediated at multiple levels, including impacting on the Out secretion system and the virulence gene regulatory network. Transcriptome analyses revealed that the abundance of a broad, but defined, set of transcripts, including many virulence factors, was altered in the dsbA mutant, identifying a new virulence regulon responsive to extracytoplasmic conditions. In conclusion, DsbA plays a crucial, multi-faceted role in the pathogenesis of Eca. Keywords: Mutant comparison