Escherichia coli
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PROVIDER: PRJNA93475 | ENA |
REPOSITORIES: ENA
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Project description:Time course analysis of genes regulated by E. coli sigma 32 (rpoH) after overexpression
| PRJNA94741 | ENA
Project description:DNA microarray analysis of genes regulated by the alternative sigma factor, sigma E (rpoE). Sigma E-dependent genes were initially identified by comparing a wild type (wt) E. coli K-12 strain that has a low level of sigma E, with a strain over-expressing sigma E (following induction of rpoE from an inducible promoter by IPTG). We monitored changes in gene expression in 4 separate time-courses after induction and used SAM (Statistical Analysis of Microarrays) to identify 75 significantly induced and 8 significantly repressed genes. Some of these genes are part of operons in which other gene members were clearly induced but were not marked as significant in our strict selection criteria. Therefore, to fully describe the sigma E regulon we expanded this set by using the statistics from SAM to analyze the reproducibility and significance of the expression ratios of all the genes adjacent to and in the same orientation as the highly significant genes. This gave 96 genes organized in 50 sigma E-dependent transcription units (TUs), of which 42 were induced and 8 were repressed. This study is detailed in Rhodius et al 2006 (PLoS Biol 4(1): e2) Keywords: time course
2005-10-13 | GSE3437 | GEO
Project description:DNA microarray analysis of genes regulated by the alternative sigma factor, sigma 32 (rpoH). Sigma 32-dependent genes were initially identified by comparing a wild type (wt) E. coli K-12 strain that has a low level of sigma 32, with a strain over-expressing sigma 32 (following induction of rpoH from an inducible promoter by IPTG). We monitored changes in gene expression in 4 separate time-courses. Because sigma 32 is negatively regulated, its activity decreases 10 min after overexpression. Consequently, to identify genes regulated by sigma 32 we analyzed the expression data for 10 min after overexpression using SAM (Statistical Analysis of Microarrays). We identified 105 genes organized in 66 separate transcription units. This study is detailed in Nonaka et al 2006 (submitted). Keywords: time course
2006-03-06 | GSE4321 | GEO
Project description:cDNA microarray analysis to identify genes regulated by the RNA chaperone, Hfq. Four experiments were performed: 1/ Hfq+ vs Hfq- strains. 269 significantly differentially regulated genes were identified by SAM (Statistical Analysis of Microarrays), of which 120 changed more than 1.5 fold (48 increased and 72 decreased in hfq-). Amongst other genes, these experiments identified significant regulation of the sigma E and sigma 32 regulons. However, only genes induced by sigma E were similarly induced in hfq-; 8 operons repressed by sigma E were not repressed in hfq-. 2/ wt vs delta rseA. RseA is the antisigma factor for sigmaE. This comparison results in elevated steady-state levels of sigma E, and confirmed induction and repression of target regulon members. 3/ hfq+ vs hfq+ rpoE overexpression. RpoE encoding sigma E was overexpressed in an hfq+ background, confirming normal regulation of the sigma E regulon. 4/ hfq+ vs hfq- rpoE overexpression. Sigma E was overexpressed in an hfq- background. This demonstrated that 8 operons normally repressed by sigma E require hfq for this repression. The simple conclusion is that sigma E regulates small RNAs that, together with Hfq, bind target mRNAs and results in their rapid degradation. This study is detailed in Guisbert et al 2007 (J Bacteriol, 189:1963-73) Keywords: Genetic modification
2007-01-01 | GSE6444 | GEO
Project description:This study examined the genes under the control of sigma32 in E. coli by moderate induction of a plasmid-borne rpoH gene under defined steady-state growth condition. Samples were taken from culture at mid log phase (OD=0.2) before or 5 minutes, 10 minutes or 15 minutes after induction. Samples were then RNA-stabilized using Qiagen RNAProtect Bacterial Reagent (Qiagen). Total RNA was then isolated using MasterPure kits (Epicentre Technologies). Purified RNA was reverse-transcribed to cDNA, labeled and hybridized to Affymetrix GeneChip E. coli Antisense Genome Arrays as recommended in the technical manual (www.affymetrix.com). Meanwhile, we measured the protein level of sigma32 during the time course. The changes of some sigma32 –dependent genes were also determined in a DnaK null mutant to examine the anti- sigma32 function of DnaK. Keywords = sigma factor Keywords = regulon Keywords = microarray Keywords = Western blot Keywords = E. coli Keywords = anti-sigma factor Keywords: time-course
2007-08-01 | GSE2140 | GEO
Project description:RpoS, an alternative sigma factor, is critical for stress response in Escherichia coli. The RpoS regulon expression has been well characterized in rich media that support fast growth and high growth yields. In contrast, though RpoS levels are high in minimal media, how RpoS functions under such conditions has not been clearly resolved. In this study, we compared the global transcriptional profiles of wild type and an rpoS mutant of E. coli grown in glucose minimal media using microarray analyses. The expression of over 200 genes was altered by loss of RpoS in exponential and stationary phases, with only 48 genes common to both conditions. The nature of the RpoS-controlled regulon in minimal media was substantially different from that expressed in rich media. Specifically, the expression of many genes encoding regulatory factors (e.g., hfq, csrA and rpoE) and genes in metabolic pathways (e.g., lysA, lysC and hisD) were regulated by RpoS in minimal media. In early exponential phase, protein levels of RpoS in minimal media were much higher than that in LB media, which may at least partly account for the observed difference in the expression of RpoS-controlled genes. Expression of genes required for flagellar function and chemotaxis was elevated in the rpoS mutant. Western blot analyses show that the flagella sigma factor FliA was expressed much higher in rpoS mutants than in WT in all phase of growth. Consistent with this, the motility of rpoS mutants was enhanced relative to WT. In conclusion, RpoS and its controlled regulators form a complex regulatory network that mediates the expression of a large regulon in minimal media.
2008-10-10 | GSE12797 | GEO
Project description:In Escherichia coli crosstalk between DNA supercoiling, nucleoid-associated proteins and major RNA polymerase σ initiation factors regulates growth phase-dependent gene transcription. We show that the highly conserved spatial ordering of relevant genes along the chromosomal replichores largely corresponds both to their temporal expression patterns during growth and to an inferred gradient of DNA superhelical density from the origin to the terminus. Genes implicated in similar functions are related mainly in trans across the chromosomal replichores, whereas DNA-binding transcriptional regulators interact predominantly with targets in cis along the replichores. We also demonstrate that macrodomains (the individual structural partitions of the chromosome) are regulated differently. We infer that spatial and temporal variation of DNA superhelicity during the growth cycle coordinates oxygen and nutrient availability with global chromosome structure, thus providing a mechanistic insight into how the organization of a complete bacterial chromosome encodes a spatiotemporal program integrating DNA replication and global gene expression.
2017-01-01 | GSE65244 | GEO
Project description:RpoS, an alternative sigma factor, is critical for stress response in Escherichia coli. The RpoS regulon expression has been well characterized in rich media that support fast growth and high growth yields. In contrast, though RpoS levels are high in minimal media, how RpoS functions under such conditions has not been clearly resolved. In this study, we compared the global transcriptional profiles of wild type and an rpoS mutant of E. coli grown in glucose minimal media using microarray analyses. The expression of over 200 genes was altered by loss of RpoS in exponential and stationary phases, with only 48 genes common to both conditions. The nature of the RpoS-controlled regulon in minimal media was substantially different from that expressed in rich media. Specifically, the expression of many genes encoding regulatory factors (e.g., hfq, csrA and rpoE) and genes in metabolic pathways (e.g., lysA, lysC and hisD) were regulated by RpoS in minimal media. In early exponential phase, protein levels of RpoS in minimal media were much higher than that in LB media, which may at least partly account for the observed difference in the expression of RpoS-controlled genes. Expression of genes required for flagellar function and chemotaxis was elevated in the rpoS mutant. Western blot analyses show that the flagella sigma factor FliA was expressed much higher in rpoS mutants than in WT in all phase of growth. Consistent with this, the motility of rpoS mutants was enhanced relative to WT. In conclusion, RpoS and its controlled regulators form a complex regulatory network that mediates the expression of a large regulon in minimal media. Experiment Overall Design: A precise rpoS deletion mutant of MG1655 was constructed using the red recombinase method. Wild type and rpoS mutants were inoculated in triplicate into M63 glucose (0.2%) minimal media at a starting OD of 0.0001 and grown aerobically at 37oC. Cultures were harvested at OD600= 0.3 in exponential phase and at OD600= 1.5 in stationary phase. For RNA extraction, cultures were mixed directly with a boiling lysis buffer containing SDS and EDTA followed by acidic hot phenol (65C) to minimize RNA degradation. RNA samples were hybridized to Affymetrix E. coli Antisense Genome Array according to Affymetrix's standard protocols.
2008-10-26 | E-GEOD-12797 | biostudies-arrayexpress
Project description:Enzyme IIANtr (encoded by ptsN gene) is a component of the nitrogen phosphotransferase system (PTS). It has previously been shown that the dephosphorylated form of EIIANtr is required for the derepression of ilvBN encoding acetohydroxy acid synthase I (AHAS I) catalyzing the first step common to biosynthesis of branched-chain amino acids. Here we examine the effect of deletion of ptsN gene on global gene expression by microarray analysis. Most of the genes down-regulated in a ptsN mutant are controlled by sigma 70, while all the up-regulated genes are controlled by sigma S. As intracellular levels of sigma factors in the ptsN mutant were similar to those of the wild-type strain, this implied that the balance of sigma activities is modified by ptsN deletion.
2010-09-28 | GSE24373 | GEO