Project description:Genetically programmed deaths play important roles in the biology of unicellular prokaryotic cells. Some gene complexes force their maintenance on the host bacterial cells by killing cells that have lost them. This form of programmed death called post-segregational killing or genetic addiction is brought about by several Type II restriction-modification gene complexes, through restriction attack on the undermethylated chromosome, and underlie their behavior as selfish mobile elements. To learn the genetic steps to death, we examined how carriage and loss of PaeR7I restriction-modification gene complex affect host Escherichia coli cells through transcriptome and experimental analyses. The PaeR7I complex was on a temperature-sensitive plasmid so that the killing was induced by a temperature shift. We used microarrays to detail the global program of gene expression underlying cell death process mediated by PaeR7I restriction-modification system in E. coli. Keywords: time course
Project description:Genetically programmed deaths play important roles in the biology of unicellular prokaryotic cells. Some gene complexes force their maintenance on the host bacterial cells by killing cells that have lost them. This form of programmed death called post-segregational killing or genetic addiction is brought about by several Type II restriction-modification gene complexes, through restriction attack on the undermethylated chromosome, and underlie their behavior as selfish mobile elements. To learn the genetic steps to death, we examined how carriage and loss of PaeR7I restriction-modification gene complex affect host Escherichia coli cells through transcriptome and experimental analyses. The PaeR7I complex was on a temperature-sensitive plasmid so that the killing was induced by a temperature shift. We used microarrays to detail the global program of gene expression underlying cell death process mediated by PaeR7I restriction-modification system in E. coli. Experiment Overall Design: Post-segregational cell killing was induced by blocking replication of a temperature sensitive plasmid carrying PaeR7I RM gene complex by shifting up the cultivation temperature. At 30℃, the permissive temperature for the plasmid replication, growth as monitored by OD660, of MG1655/pTN9 (r+m+) was indistinguishable from those of MG1655/pTN11 (r-m+) and MG1655/pHSG415 (vector). Cell death was observed at least 4 h after the temperature shift only in MG1655/pTN9 (r+m+) as in the previous works; the increase in viable cell counts stopped and resulted in decrease of cell viability. To analyze global gene expression when cells went to death, we performed transcriptome analysis 0 h, 1h, 1 h 50 min, and 3h after the temperature shift. We used Affimetrix E. coli antisense genome array. Experiments were performed independently twice.
Project description:RNA-seq analysis of gene expression in pneumococcus D39 strains with the SpnIII type I restriction modification system locked into one of three available phasotypes.
Project description:Host acquisition by bacteriophages (phages) often entails modulation, appropriation, or inhibition of components and processes central to bacterial gene expression. Among these, small non‑coding RNAs (sRNAs) are major regulators of RNA fate and frequently rely on the conserved RNA chaperone Hfq to engage their cognate targets. Although phages are known to encode specialised proteins and sRNAs to manipulate host gene expression, it has remained unclear whether they also co‑opt host‑encoded sRNAs for their own gene regulatory needs. We show that transcriptome‑wide Hfq‑mediated RNA–RNA interactions are broadly destabilised during T2 phage infection of Escherichia coli. We further demonstrate that the conserved bacterial sRNA ArcZ is co-opted by T2 to promote expression of a conserved phage operon that includes a protein inhibiting a bacterial restriction–modification system. ArcZ achieves this by preventing RNase E–mediated degradation of the transcript originating from the phage operon. Our study provides the first evidence of an evolutionary strategy in which a phage leverages a nucleic acid host factor to fulfil its own gene expression requirements.
Project description:These E. coli strains were grown with various signaling molecules and the expression profiles were determined. Keywords: addition of quorum and host hormone signals
Project description:PhoP is considered a regulator of virulence despite being conserved in both pathogenic and non-pathogenic Enterobacteriaceae. While Escherichia coli strains represent both non-pathogenic commensal isolates and numerous virulent pathotypes, the PhoP virulence regulator has only been studied in commensal E. coli. To better understand how conserved transcription factors contribute to virulence, we characterized PhoP in pathogenic E. coli. Loss of phoP significantly attenuated E. coli during extraintestinal infection. This was not surprising since we demonstrated that PhoP differentially regulated the transcription of >600 genes. In addition to survival at acidic pH and resistance to polymyxin B, PhoP was required for repression of motility and oxygen-independent changes in the expression of primary dehydrogenase and terminal reductase respiratory chain components. All phenotypes have in common a reliance on an energized membrane. Thus, we hypothesized that PhoP mediated these effects by regulating genes that generate a proton motive force. Indeed, bacteria lacking PhoP exhibited a hyper-polarized membrane, and dissipation of the transmembrane electrochemical gradient increased the susceptibility of the phoP mutant to acidic pH, while inhibiting respiratory generation of the proton gradient restored resistance to antimicrobial peptides independent of lipopolysaccharide modification. These findings demonstrate a connection between PhoP, virulence, and the energized state of the membrane.
Project description:The purpose of this study is to determine whether the presence of pathogenic Escherichia coli in colon is associated with psychiatric disorders.
Project description:Gene expression profiles of Escherichia coli, grown anaerobically, with or without Acacia mearnsii (Black wattle) extract were compared to identify tannin-resistance strategies. The cell envelope stress protein, spy, and the multidrug transporter-encoding mdtABCD, both under the control of the BaeSR two-component regulatory system, were significantly up-regulated in the presence of tannins. BaeSR mutants were more tannin-sensitive than their wild-type counterparts. Keywords: tannin resistance
Project description:Despite the characterization of many aetiologic genetic changes. The specific causative factors in the development of sporadic colorectal cancer remain unclear. This study was performed to detect the possible role of Enteropathogenic Escherichia coli (EPEC) in developing colorectal carcinoma.