Project description:Escherichia coli is an important human pathogen, among others a cause of severe diarrhea diseases and urinary tract infections. The ability to distinguish different pathogenic E. coli subspecies is crucial for correct treatment of the infection. Characterization and quantification of clinical isolates proteomes can provide details of the organisms’ metabolism and specific virulence factors. We performed a systematic quantitative proteomic analysis on a representative selection of 16 pathogenic and 2 commensal E. coli strains, together with 5 pathogenic Shigella strains. The analysis yielded a dataset of more than 4 thousand proteins, with an average of 2 thousand proteins per strain and 980 proteins common to all strains. Statistical comparison of label-free quantitative levels of 750 proteins, which were quantified in all strains, revealed that levels of a majority of the shared proteins vary substantially among specific strains. Theses quantitative protein profiles clearly distinguished E. coli strains from Shigella and largely separated commensal E. coli strains from intestinal and extraintestinal E. coli isolates.
Project description:Pathogenic biofilms have been associated with persistent infections due to high resistance to antimicrobial agents while commensal biofilms often fortify host immune system. Hence, controlling biofilm formation of both pathogenic bacteria and commensal bacteria is important in bacteria-related diseases. We investigated the effect of plant flavonoids on biofilm formation of both enterohemorrhagic Escherichia coli O157:H7 and three commensal E. coli K-12 strains. Phloretin abundant in apples markedly reduced E. coli O157:H7 biofilm formation without affecting the growth of planktonic cells while phloretin did not harm commensal E. coli K-12 biofilms. Also, phloretin reduced E. coli O157:H7 attachment to human colon epithelial cells. Global transcriptome analyses revealed that phloretin repressed toxin genes (hlyE and stx2), autoinducer-2 importer genes (lsrACDBF), a curli gene (csgA), and a dozens of prophage genes in E. coli O157:H7 cells. Electron microscopy confirmed that phroretin reduced the curli production in E. coli O157:H7. In addition, phloretin suppressed TNF-α-induced inflammatory response in vitro using human colonic epithelial cells. Moreover, in the trinitrobenzene sulfonic acid (TNBS)-induced rat colitis model, phloretin significantly ameliorated colon inflammation and body weight loss. Taken together, our results suggest that phloretin may act as an inhibitor of E. coli O157:H7 biofilm formation as well as anti-inflammatory agent on inflammatory bowel diseases while leaving beneficial commensal E. coli biofilm intact.
Project description:Escherichia coli, the common inhabitant of the mammalian intestine, exhibits considerable intraspecies genomic variation, which has been suggested to reflect adaptation to different ecological niches. Also, regulatory trade-offs, e.g., between catabolic versatility and stress protection, are thought to result in significant physiological differences between strains. For these reasons, the relevance of experimental observations made for “domesticated” E. coli strains with regard to the behaviour of this species in its natural environments is often questioned and frequently doubts are raised on the status of E. coli as a defined species. We therefore investigated the variability of important eco-physiological functions such as carbon substrate uptake and breakdown capabilities as well as stress defence mechanisms in the genomes of commensal and pathogenic E. coli strains. Furthermore, eco-physiological properties of environmental strains were compared to standard laboratory strain K-12 MG1655. Catabolic, stress protection, and carbon- and energy source transport operons showed a very low intraspecies variability in 57 commensal and pathogenic E. coli. Environmental isolates adapted to glucose-limited growth in a similar way as E. coli MG1655, namely by increasing their catabolic flexibility and by inducing high affinity substrate uptake systems. Our results indicate that the major eco-physiological properties are highly conserved in the natural population of E. coli. This questions the proposed dominant role of horizontal gene transfer for niche adaptation. Keywords: CGH, E. coli, gDNA, environmental strains, eco-physiology
Project description:Escherichia coli, the common inhabitant of the mammalian intestine, exhibits considerable intraspecies genomic variation, which has been suggested to reflect adaptation to different ecological niches. Also, regulatory trade-offs, e.g., between catabolic versatility and stress protection, are thought to result in significant physiological differences between strains. For these reasons, the relevance of experimental observations made for “domesticated” E. coli strains with regard to the behaviour of this species in its natural environments is often questioned and frequently doubts are raised on the status of E. coli as a defined species. We therefore investigated the variability of important eco-physiological functions such as carbon substrate uptake and breakdown capabilities as well as stress defence mechanisms in the genomes of commensal and pathogenic E. coli strains. Furthermore, eco-physiological properties of environmental strains were compared to standard laboratory strain K-12 MG1655. Catabolic, stress protection, and carbon- and energy source transport operons showed a very low intraspecies variability in 57 commensal and pathogenic E. coli. Environmental isolates adapted to glucose-limited growth in a similar way as E. coli MG1655, namely by increasing their catabolic flexibility and by inducing high affinity substrate uptake systems. Our results indicate that the major eco-physiological properties are highly conserved in the natural population of E. coli. This questions the proposed dominant role of horizontal gene transfer for niche adaptation. Keywords: comparative genomic hybridisation
Project description:The establishment of bacterial infections at epithelial surfaces is determined by the balance of virulence attributes of the pathogen with the activity of innate host defenses. Polymorphonuclear leukocytes (PMN) are key responders in many bacterial infections, but the mechanisms by which pathogens subvert these early responses to establish infection are largely undefined. Here, we model these early interactions between human PMN and the primary cause of urinary tract infections, namely uropathogenic Escherichia coli (UPEC). Our objective was to define virulence phenotypes of uropathogens (as compared with laboratory and commensal E. coli strains) that permit evasion of PMN activity. We found that UPEC strains resist phagocytic killing and dampen the production of antimicrobial reactive oxygen species by PMNs. Analysis of the global transcriptional responses of PMN to E. coli strains revealed that UPEC exposure downregulates the expression of PMN genes involved in proinflammatory signaling and PMN chemotaxis, adhesion, and migration. Consistent with these data, UPEC attenuated transepithelial neutrophil recruitment in an in vitro model of acute infection. We propose that these UPEC strategies are important in the establishment of epithelial infection, and that the findings are germane to a range of bacterial infections at epithelial surfaces. We used microarrays to detail the global program of gene expression in human neutrophils in response to a uropathogenic bacteria compared to a closely related non-pathogenic strain relative to control samples with no bacteria. Our goal was to elucidate a pathogen-specific response. We chose an early time point of 60 minutes to evaluate the accute response to infection. Human neutrophils were exposed to pathogenic or commensal Escherichia coli for RNA extraction and hybridization on Affymetrix microarrays
Project description:AbuOun2009 - Genome-scale metabolic network
of Salmonella typhimurium (iMA945)
This model is described in the article:
Genome scale reconstruction
of a Salmonella metabolic model: comparison of similarity and
differences with a commensal Escherichia coli strain.
AbuOun M, Suthers PF, Jones GI,
Carter BR, Saunders MP, Maranas CD, Woodward MJ, Anjum MF.
J. Biol. Chem. 2009 Oct; 284(43):
29480-29488
Abstract:
Salmonella are closely related to commensal Escherichia coli
but have gained virulence factors enabling them to behave as
enteric pathogens. Less well studied are the similarities and
differences that exist between the metabolic properties of
these organisms that may contribute toward niche adaptation of
Salmonella pathogens. To address this, we have constructed a
genome scale Salmonella metabolic model (iMA945). The model
comprises 945 open reading frames or genes, 1964 reactions, and
1036 metabolites. There was significant overlap with genes
present in E. coli MG1655 model iAF1260. In silico growth
predictions were simulated using the model on different carbon,
nitrogen, phosphorous, and sulfur sources. These were compared
with substrate utilization data gathered from high throughput
phenotyping microarrays revealing good agreement. Of the
compounds tested, the majority were utilizable by both
Salmonella and E. coli. Nevertheless a number of differences
were identified both between Salmonella and E. coli and also
within the Salmonella strains included. These differences
provide valuable insight into differences between a commensal
and a closely related pathogen and within different pathogenic
strains opening new avenues for future explorations.
This model is hosted on
BioModels Database
and identified by:
MODEL1507180009.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:Escherichia coli, the common inhabitant of the mammalian intestine, exhibits considerable intraspecies genomic variation, which has been suggested to reflect adaptation to different ecological niches. Also, regulatory trade-offs, e.g., between catabolic versatility and stress protection, are thought to result in significant physiological differences between strains. For these reasons, the relevance of experimental observations made for âdomesticatedâ E. coli strains with regard to the behaviour of this species in its natural environments is often questioned and frequently doubts are raised on the status of E. coli as a defined species. We therefore investigated the variability of important eco-physiological functions such as carbon substrate uptake and breakdown capabilities as well as stress defence mechanisms in the genomes of commensal and pathogenic E. coli strains. Furthermore, eco-physiological properties of environmental strains were compared to standard laboratory strain K-12 MG1655. Catabolic, stress protection, and carbon- and energy source transport operons showed a very low intraspecies variability in 57 commensal and pathogenic E. coli. Environmental isolates adapted to glucose-limited growth in a similar way as E. coli MG1655, namely by increasing their catabolic flexibility and by inducing high affinity substrate uptake systems. Our results indicate that the major eco-physiological properties are highly conserved in the natural population of E. coli. This questions the proposed dominant role of horizontal gene transfer for niche adaptation. Keywords: comparative genomic hybridisation Standard approach for comparative genomic hybrisisation, 5 environmental strains were analysed on commercial E. coli MG1655 arrays (MWG), for each strains, biological replicates were done (separate LB cultures)
Project description:Background: Based on 32 Escherichia coli and Shigella genome sequences, we have developed an E. coli pan-genome microarray. Publicly available genomes were annotated in a consistent manor to define all currently known genes potentially present in the species. The chip design was evaluated by hybridization of DNA from two sequenced E. coli strains, K-12 MG1655 (a commensal) and O157:H7 EDL933 (an enterotoxigenic E. coli). A dual channel and single channel analysis approach was compared for the comparative genomic hybridization experiments. Moreover, the microarray was used to characterize four unsequenced probiotic E. coli strains, currently marketed for beneficial effects on the human gut flora. Results: Based on the genomes included in this study, we were able to group together 2,041 genes that were present in all 32 genomes. Furthermore, we predict that the size of the E. coli core genome will approach ~1,560 essential genes, considerably less than previous estimates. Although any individual E. coli genome contains between 4,000 and 5,000 genes, we identified more than twice as many (11,872) distinct gene groups in the total gene pool (“pan-genome”) examined for microarray design. Benchmarking of the design based on sequenced control strain samples demonstrated a high sensitivity and relatively low false positive rate. Moreover, the array was highly sufficient to investigate the gene content of apathogenic isolates, despite the strong bias towards pathogenic E. coli strains that have been sequenced so far. Our analysis of four probiotic E. coli strains demonstrate that they share a gene pool very similar to the E. coli K-12 strains but also show significant similarity with enteropathogenic strains. Nonetheless, virulence genes were largely absent. Strain-specific genes found in probiotic E. coli but absent in E. coli K12 were most frequently phage-related genes, transposases and other genes related to mobile DNA, and metabolic enzymes or factors that may offer colonization fitness, which together with their asymptomatic nature may explain their nature. Conclusion: This high-density microarray provides an excellent tool for characterizing either DNA content or gene expression from unknown E. coli strains. Keywords: Comparative genomic hybridizations
Project description:Pathogenic biofilms have been associated with persistent infections due to high resistance to antimicrobial agents while commensal biofilms often fortify host immune system. Hence, controlling biofilm formation of both pathogenic bacteria and commensal bacteria is important in bacteria-related diseases. We investigated the effect of plant flavonoids on biofilm formation of both enterohemorrhagic Escherichia coli O157:H7 and three commensal E. coli K-12 strains. Phloretin abundant in apples markedly reduced E. coli O157:H7 biofilm formation without affecting the growth of planktonic cells while phloretin did not harm commensal E. coli K-12 biofilms. Also, phloretin reduced E. coli O157:H7 attachment to human colon epithelial cells. Global transcriptome analyses revealed that phloretin repressed toxin genes (hlyE and stx2), autoinducer-2 importer genes (lsrACDBF), a curli gene (csgA), and a dozens of prophage genes in E. coli O157:H7 cells. Electron microscopy confirmed that phroretin reduced the curli production in E. coli O157:H7. In addition, phloretin suppressed TNF-α-induced inflammatory response in vitro using human colonic epithelial cells. Moreover, in the trinitrobenzene sulfonic acid (TNBS)-induced rat colitis model, phloretin significantly ameliorated colon inflammation and body weight loss. Taken together, our results suggest that phloretin may act as an inhibitor of E. coli O157:H7 biofilm formation as well as anti-inflammatory agent on inflammatory bowel diseases while leaving beneficial commensal E. coli biofilm intact. For the microarray experiments, E. coli O157:H7 EDL933 was inoculated in 25 ml of LB in 250 ml flasks with overnight cultures that were diluted at 1:100. Cells were shaken at 100 rpm and 37°C for 7 hrs. Cells were immediately chilled with dry ice and 95% ethanol (to prevent RNA degradation) for 30 sec before centrifugation in 50 ml centrifuge tubes at 13,000 g for 2 min; cell pellets were frozen immediately with dry ice and stored -80°C. RNA was isolated using Qiagen RNeasy mini Kit (Valencia, CA, USA). To eliminate DNA contamination, Qiagen RNase-free DNase I was used to digest DNA. RNA quality was assessed by Agilent 2100 bioanalyser using the RNA 6000 Nano Chip (Agilent Technologies, Amstelveen, The Netherlands), and quantity was determined by ND-1000 Spectrophotometer (NanoDrop Technologies, Inc., DE, USA).
Project description:Comparative genomic hybridization between Escherichia coli strains to determine core and pan genome content of clinical and environmental isolates