Project description:Purpose: In this work, we evaluated the role of two indicative species, Citrobacter werkmanii (CW) and Escherichia albertii (EA), in the virulence of two DEC pathotypes, Shiga toxin-producing (STEC) and enteroaggregative (EAEC) Escherichia coli. Methods: To determine the effect of supernatant obtained from CW and EA cultures in STEC strain 86-24 and EAEC strain 042 gene expression, a RNA-seq analysis was performed. T84 cells were infected with DEC strains in the presence or absence of supernatant from EA and IL-8 secretion was evaluated. The effect of supernatant from EA on the growth and adherence of STEC and EAEC to T84 cells was also evaluated. Finally, we studied the participation of long polar fimbriae (Lpf) in STEC and plasmid-encoded toxin (Pet) in EAEC during DEC infection in the presence of supernatant from EA. Results: RNA-seq analysis revealed that several virulence factors in STEC and EAEC were up-regulated in the presence of supernatants from CW and EA. Interestingly, an increase in the secretion of IL-8 was observed in T84 cells infected with STEC or EAEC in the presence of a supernatant from EA. Similar results were observed with the supernatants obtained from clinical strains of E. albertii. Supernatant from EA had no effect on the growth of STEC and EAEC, or on the ability of these DEC strains to adhere to intestinal epithelial cells. Finally, we found that Pet toxin in EAEC was up-regulated in the presence of a supernatant from EA. In STEC, using mutant strains for Lpf fimbriae, our data suggested that these fimbriae might be participating in the increase of IL-8 induced by STEC on intestinal epithelial cells in the presence of a supernatant from EA. Conclusion:Supernatant obtained from an indicative species of DEC-positive diarrhea could modulate gene expression in STEC and EAEC, and IL-8 secretion induced by these bacteria. These data provide new insights into the effect of gut microbiota species in the pathogenicity of STEC and EAEC.
Project description:The purpose of this study was to identify the RNA cleavage targets and specificities of 9 endoribonuclease toxins from toxin-antitoxin systems in E. coli MG1655.
Project description:The purpose of our study was to examine the effect of enterotoxigenic E. coli (ETEC) heat-stable toxin (ST) on global T84 gene expression at selected time points following intoxication, with the goal of understanding the functional effects of ST on host epithelium. RNASeq analysis relvealed that ST alters inflammatory gene expression, including the IL-1 family member IL33, which is induced downstream of cGMP.
Project description:Bacterial toxin-antitoxin systems are thought to help bacteria to reduce their metabolism in various stressful conditions. Many toxins of the bacterial toxin-antitoxin systems are ribonucleases. Such toxins have been mostly viewed as degraders of mRNA, however recently it was demonstrated that they are also capable of cleaving non-coding RNA. MazF toxin is also hypothesized to reprogram E. colis translational machinery. Current cDNA libraries are part of a project which aims to identify the major RNA cleavage sites (in mRNA, rRNA and regulatory non-coding RNA) of MazF and MqsR toxins in E. coli. We wanted to elaborate on the roles of MazF and MqsR in E. coli: is MazF really involved in reprogramming the translational machinery or is MazF, along with MqsR, just a robust cleaver of RNA? We extracted total RNA from cultures where the expression of MazF or MqsR was induced for 2h and from cultures that had been recovering from toxin production for 30 minutes; RNA from log phase culture was used as the control. We used strand specific random primed paired end RNA sequencing data to locate the major cleavage sites. To map the cleavage sites, we counted 5’ end stacks of forward reads in each genomic position and compared them with total coverage. MazF and MqsR cleave at specific recognition sequences, ˇACA and GˇC respectively, which allowed us to eliminate the false positives. One of our initial aims was also to look for irregular RNA ligation events following toxin expression, thus we used long, 300 base reads in sequencing.
Project description:Changes in endothelial phenotype induced by E. coli-derived Shiga toxins (Stx) are believed to play a critical role in the pathogenesis of hemolytic uremic syndrome. Stx inactivate host ribosomes, but also alter gene expression at concentrations that minimally affect global protein synthesis. The effect of Stx on the gene expression profile of human microvascular endothelial cells was examined using the Affymetrix HG-U133A platform. Data were processed using 13 different methods and revealed 369 unique differentially expressed genes, 318 of which were up-regulated and 51 of which were down-regulated. These studies implicated activation of the CXCR4/CXCR7/SDF-1 chemokine pathway in Stx-mediated pathogenesis. Primary human dermal microvascular endothelial cells were treated with vehicle or Shiga toxin (10 fM, 24 h, n = 6) and changes in steady-state mRNA levels were determined by hybridization to Affymetrix HG-U133A arrays
Project description:Here, we adapted and improved our FASTBAC-Seq method originally designed in Helicobacter pylori to investigate T1TAs in the model organism Escherichia coli. Our approach combines a life and death selection with deep-sequencing to assess the killing capability of a toxin and obtain an overview of single-nucleotide substitutions suppressing the toxin expression or activity in absence of its antitoxin. As a proof of concept, we revisited the regulation of the plasmidic hok/Sok T1TA system.
Project description:The stress effect of 100 uM sodium tetrachloropalladate (II) was evaluated in Escherichia coli K-12 BW25113 strain on the transcriptome level
Project description:Transcriptomes of 24 clinical strains of E. coli O157:H7 that differ phylogenetically and by Shiga toxin profiles were compared after 30 min co-incubation with epithelial cells.