Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Variation in the Genomic islands of porcine enteropathogenic E. coli strains of serogroup O45 revealed by CGH and PCR.

ABSTRACT: Background: Members of E. coli serogroup O45 are porcine enteropathogenic E. coli (PEPEC) strains which cause post-weaning diarrhea and produce characteristic attaching and effacing (A/E) lesions. Most of O45 PEPEC strains possess the locus of enterocyte effacement (LEE), encoding the virulence factors for A/E lesions, and often possess the paa gene, which is thought to contribute to the early stages of PEPEC virulence. Methodology: Nine O45 PEPEC strains and a rabbit enteropathogenic (REPEC) strain, known to produce A/E lesions, were characterized using an E. coli O157-E. coli K12 whole genome microarray and a virulence gene-specific microarray, and by PCR experiments. Results: Based on their virulence genes profiles, the 10 strains were characterized as atypical EPEC. The differences in their genomes pointed to two distinct evolutionary groups of O45 PEPEC, Group I and Group II, and to the contribution these genetic differences have on virulence in pigs. Group I contained the REPEC strain and four O45 PEPEC strains known to induce severe A/E lesions in challenged pigs whereas Group II was composed of five other O45 PEPEC strains which induced less severe or no A/E lesions in challenged pigs. Significant differences between Groups I and II were found in the presence or absence of 50 O-Islands (OIs) or S-loops and 13 K-islands (KIs) or K-loops, including the virulence-associated islands OI#1 (S-loop#1), OI#47 (S-loop#71), OI#57 (S-loop#85), OI#71 (S-loop#108), OI#115, OI#122, and OI#154 (S-loop#253). 10 samples, with two microarrays per sample. Each microarray includes duplicates of every spot.

ORGANISM(S): Escherichia coli

SUBMITTER: Victor Gannon

PROVIDER: E-GEOD-17036 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Two distinct groups of porcine enteropathogenic Escherichia coli strains of serogroup O45 are revealed by comparative genomic hybridization and virulence gene microarray.

Bruant Guillaume G Zhang Yongxiang Y Garneau Philippe P Wong Justin J Laing Chad C Fairbrother John M JM Gannon Victor P J VP Harel Josée J

BMC genomics 20090826

<h4>Background</h4>Porcine enteropathogenic Escherichia coli (PEPEC) strains of serogroup O45 cause post-weaning diarrhea and produce characteristic attaching and effacing (A/E) lesions. Most O45 PEPEC strains possess the locus of enterocyte effacement (LEE), encoding the virulence factors required for production of A/E lesions, and often possess the paa gene, which is thought to contribute to the early stages of PEPEC pathogenicity. In this study, nine O45 PEPEC strains and a rabbit enteropatho ...[more]

PMID: 19709428

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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 (âpan-genomeâ) 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. Factorial design: Each of four test samples (G 1/2, G3/10, G 4/9, G5) are co-hybridized with two control strain samples (K-12 MG1655 and O157:H7 EDL933). Additional replicate co-hybridizations are included of the two control strain samples (O157:H7 EDL933 vs. K-12 MG1655).

Project description:DNA microarray analysis was used to compare the differential gene-expression profiles between Leptospira interrogans serovar Lai type strain 56601 and its corresponding attenuated strain IPAV. A 22 kb genomic island covering a cluster of 34 genes (LA0186 to LA0219) was actively expressed in both strains but concomitantly up-expressed in strain 56601 in contrast to that of IPAV. RT-PCR assays proved that the gene cluster comprised five transcripts. Gene annotation of this cluster revealed characteristics of a putative prophage-like remnant with at least 8 out of 34 CDSs encoding prophage-like proteins, of which, LA0195 is probably a putative prophage CI-like regulator. The transcription initiation activities of putative promoter-regulatory sequences of transcripts I, II and III, all proximal to LA0195, were further analyzed in the Escherichia coli promoter probe vector pKK232-8 by assaying the reporter CAT enzyme activities. The strong promoter activities of both transcripts I and II indicated by the E. coli CAT assay were well correlated with the in vitro sequence-specific binding of the recombinant LA0195 protein to the corresponding promoter probes detected by the electrophoresis mobility shift assay. On the other hand, the promoter activity of transcript III was very low in E. coli and failed to show active binding to LA0195 in vitro. These results suggested that LA0195 is likely involved in the transcription of transcripts I and II. However, the identical complete DNA sequences of this prophage remnant from these two strains strongly suggests that possible regulatory factors or signal transduction systems resided outside of this region within the genome maybe responsible for the differential expression profiling in these two strains. Keywords: Differential expression of L.interrogans 56601 and IPAV in 37Â°C The microarray chip was prepared as previously described (42). In brief, the 3528 protein coding sequences (CDSs) successfully amplified by PCR were printed in triplicate on the slides as probes. Three expression profiling experiments were performed via reverse transcription using Superscript (Invitrogen) and with one experiment having the cDNA of IPAV labeled by Cy3 and of 56601 labeled by Cy5, while the other two having the cDNA of 56601 labeled by Cy3 and of IPAV labeled by Cy5. The unincorporated dye was removed using a QIAquick Nucleotide Removal Kit (Qiagen) as specified by the manufacturer's protocol. Samples were hybridized at 42Â°C for 16h, and then washed as described in the manual. Hybridization experiments were performed in triplicate using cDNA derived from three different cultures of virulent strain 56601 and avirulent strain IPAV grown at 37Â°C. The hybridized slides were scanned and analyzed by Tiffsplit (Agilent) to calculate the signal intensities and to determine the presence or absence of each CDS. The data were then normalized, and their backgrounds were defined using GeneSpring 4.0 (Silicon Genetics). The GeneSpring software was used to further analyze the transcription patterns. To identify genes with significantly altered expression levels, cutoff values for expression level ratios 1.5 were used to filter genes with changes (n-fold) greater than Â±1.5 in three independent biological samples (27, 48, 50). Studentâs t test analysis of variance was used to compare the mean expression levels of the test and reference samples. Genes with significant differential expression levels (P < 0.05) were selected.

Dataset Information

Variation in the Genomic islands of porcine enteropathogenic E. coli strains of serogroup O45 revealed by CGH and PCR.

Publications

Two distinct groups of porcine enteropathogenic Escherichia coli strains of serogroup O45 are revealed by comparative genomic hybridization and virulence gene microarray.

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