Project description:Global response to ciprofloxacin in low level quinolone resistant Escherichia coli: a shorter path to survival. Background: Bactericidal activity of quinolones in bacteria has been related to a combination of DNA fragmentation, ROS production and programmed dead cell systems. Subjacent molecular systems responsible for reduction of bactericidal effect in low-level quinolone resistance (LLQR) phenotypes remain to be clarified. To answer this question and to define new possible antimicrobial targets, the transcriptomic profile in isogenic Escherichia coli harbouring quinolone resistance mechanisms in the presence of ciprofloxacin was evaluated. Materials and methods: E. coli 25922 was used as background strain. Four LLQR isogenic strains were tested for transcriptomic assays: ATCC 25922 (wild-type), EC14 (coding for QnrS1), EC19 (marR deletion and coding for QnrS1) and EC24 (Ser83Leu substitution in GyrA and coding for QnrS1). Cells in exponential phase (DO600=0.4) were exposed to 1 mg/L of ciprofloxacin (breakpoint for reduced susceptibility according to CLSI) during 1 hour and, further, RNA was purified. Gene expression analysis was performed using AGILENT technology. Data obtained for each strain were always normalized to the wild-type E. coli ATCC 25922. Specific ROS modulation targets were validated by genetic and biochemical approach. Results: A radical differential response to ciprofloxacin in LLQR strains, either up or downregulation, was observed (proportional to the MIC values). Multiple genes implicated in ROS production (related to TCA cycle, aerobic respiration or detoxification systems) were upregulated (sdhC up to 63.5-folds) in LLQR mutants. SOS system components were downregulated (recA up to 30.7-folds). yihE, coding for a protective kinase of programmed cell death, was also upregulated (up to 5.2-folds). SdhC inhibition sensitized LLQR phenotypes (up to Log=2.3 after 24 hours). Conclusions: At clinical relevant concentration of ciprofloxacin, the pattern of genes expression of critical systems for bacterial survival and mutant development were significantly modified in LLQR phenotypes. This approach allowed validating ROS modulation as an interesting target in terms of bacterial sensitization.
Project description:Purpose: We use the gene expression data to estimate the effects of tetracycline on gene expression and average ribosome density. Methods: The mRNAs were extracted with TRIzol reagent. The mRNAs were fragmented into 280 bp and the sequencing process was conducted on HiSeq 2500 platform. We use cutadapt, bowtie2, Plastid and DEseq2 software to analyze the expression levels of genes in two Escherichia coli strains. Results: The gene expression in EF4 knockout Escherichia coli strain was similar with BW25113 strain under normal condition. Under tetracycline treatment, many genes' expression were differentially regulated. Interestingly, we found that the gene expression of ribosomal proteins was up-regulated in WT strain comparing with EF4 knockout E. coli strain. Conclusions: Our results suggest that EF4 affects the average ribosome density and global gene expression in two Escherichia coli strain under tetracycline treatment.
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:NsrR is a nitric oxide sensitive regulator of transcription. In Escherichia coli, NsrR is a repressor of the hmp gene encoding the flavohemoglobin that detoxifies nitric oxide. Several other transcription units (including ytfE, ygbA and hcp-hcr) are known to be subject to regulation by NsrR. In this study, chromatin immunoprecipitation and microarray analysis was used to identify NsrR binding sites in the chromosome of Escherichia coli strain MG1655. Keywords: ChIP-chip
Project description:Here, we investigated the impact of Stx2 phage carriage on Escherichia coli (E. coli) K-12 MG1655 host gene expression. Using quantitative RNA-seq analysis, we compared the transcriptome of naïve MG1655 and the lysogens carrying the Stx2 phage of the 2011 E. coli O104:H4 outbreak strain or of the E. coli O157:H7 strain PA8, which share high degree of sequence similarity.
Project description:Investigation of whole genome gene expression level changes in a Escherichia coli MG1655 K-12 ∆fnr mutant, compared to the wild-type strain. The mutations engineered into this strain produce a strain lacking the FNR protein.
Project description:To compare transcriptional profiling of a gadE-, hdeA-, or hdeD- deficient strain to wild type in E. coli under minimum medium conditions. These genes are included in the GAD cluster genes, which are involved in the glutamic acid-dependent acid resistance (GAD) in E. coli. Goal was to determine the GadE, HdeA, or HdeD regulon in E. coli. Biological replicates: 2 replicates.