Project description:Fis and H-NS are two well-known NAPs in proteobacteria which play crucial role in both genome organization and gene regulation. However, the global effects of Fis and H-NS on gene expression remain unclear. Here, to decipher transcriptional regulatory roles of Fis and H-NS we have performed RNA-sequencing to compare gene expression between the wild-type E. coli and its knockout mutants for fis and hns. We integrated our RNA-seq results with publically available ChIP-seq data to define direct and indirect regulation by Fis and H-NS. The regulatory networks thus provide a comprehensive view of coordinated regulatory roles for these important nucleoid-associated proteins.
Project description:We have performed ChIP-Seq experiment for the global regulators, CRP and Fis in early and mid exponential growth phases respectively in Escherichia coli K12 MG1655. The dataset contains the genome wide binding patterns of Fis and CRP in the wildtype and the mutant strains
Project description:The only target locus of transcription factor BglJ known to date is the bgl operon, and activation of bgl by BglJ requires RcsB. Transcription factor LeuO is involved in stress responses and known as antagonist of H-NS. To identifiy novel targets of BglJ, we overexpressed BglJ in Escherichia coli K12 and measured differential gene expression by performing DNA microarray analysis. Moreover, to analyze whether all targets of BglJ require RcsB, we overexpressed BglJ in an rcsB deletion background. In addition, we overexpressed LeuO to identifiy targets of LeuO.
Project description:To fit within the confines of the cell, bacterial chromosomes are highly condensed into a structure called the nucleoid. Despite the high degree of compaction in the nucleoid, the genome remains accessible to essential biological processes, such as replication and transcription. Here, we present the first high-resolution chromosome conformation capture-based molecular analysis of the spatial organization of the Escherichia coli nucleoid during rapid growth in rich medium and following an induced amino acid starvation that promotes the stringent response. Our analyses identify the presence of origin and terminus domains in exponentially growing cells. Moreover, we observe an increased number of interactions within the origin domain and significant clustering of SeqA-binding sequences, suggesting a role for SeqA in clustering of newly replicated chromosomes. By contrast, ‘histone-like’ protein (i.e. Fis, IHF and H-NS) binding sites did not cluster, and their role in global nucleoid organization does not manifest through the mediation of chromosomal contacts. Finally, genes that were downregulated after induction of the stringent response were spatially clustered, indicating that transcription in E. coli occurs at transcription foci.
Project description:Leafy green vegetables, such as lettuce, have been increasingly implicated in outbreaks of foodborne illnesses due to contamination by Escherichia coli O157:H7. While E. coli can survive in soils, colonize plants, and survive on produce, very little is known about the interaction of E. coli with the roots of growing lettuce plants. In these studies, a combination of microarray analyses and surface enhanced Raman spectroscopy (SERS) were used to gain a comprehensive understanding of bacterial genes involved in the colonization and growth of E. coli O157:H7 on lettuce roots and compared to E. coli K12 using a hydroponic system (HS) which we have reported in the previous studies. Using microarray, after three days of interaction with lettuce roots, 94 and 109 genes of E. coli O157:H7 were significantly up-regulated and down-regulated at least 1.5 fold, respectively. Only 8 genes were also found in the E. coli K12 up-regulated genes. No genes were found in the down-regulated genes clusters between those two strains. For E. coli O157:H7, forty out of the 94 up-regulated genes (43%) were involved in protein synthesis and were highly repressed compared to 40 out of 193 (23%) E. coli K12 up-regulated genes associated with protein synthesis. The wildtype of E.coli O157:H7 colonized two log CFU per root less compared to E. coli K12. Genes involved in biofilm modulation (bhsA and ybiM) were significantly up-regulated in E. coli O157:H7 and curli production (crl and csgA) were found important for E. coli K12 to attach to lettuce roots in the previous studies. BhsA mutant of E. coli O157:H7 was impaired in the colonization of lettuce roots. The SERS spectra of E. coli K12 and O157 controls (cells without interacting with roots) were very similar. The spectra of E. coli K12 and O157 exposed to the hydroponic system (HS) showed some differences in the nucleic acid, protein, and lipid regions compared with controls. The spectra of E. coli K12 HS cells exhibited significant differences compared to spectra from E. coli O157 HS cells in the RNA and protein regions. The overall band intensity of amide regions declined for E. coli O157 HS cells, while it increased for E. coli K12 HS cells. The intensity of the RNA bands of E. coli K12 HS cells were also found much higher than those of E. coli O157 HS cells. These findings were in agreement to our Microarray data. Our microarray and SERS data showed that E. coli K12 and O157:H7 behavior dramatically differently in colonizing on lettuce roots. Compared to K12, E. coli O157:H7 colonized less efficiently on lettuce roots.
Project description:Proteomics analysis in Escherichia coli K12 (E. coli K12) at DMP concentrations of 0 mg·kg-1 (CK) and 80 mg·kg-1 (DMP) revealed the toxicity of DMP