Transcriptional responses of Escherichia coli k12 TPEN
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ABSTRACT:
ORGANISM(S): Escherichia coli
SUBMITTER: Michael Crowder
PROVIDER: E-GEOD-11303 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:We probed the mechanism of cross-regulation of osmotic and heat stress responses by characterizing the effects of high osmolarity (0.3M vs. 0.0M NaCl) and temperature (43oC vs. 30oC) on the transcriptome of Escherichia coli K12 using E. coli Genome 2 Array (Affymetrix, Inc.). Independent array hybridizations were carried out for 3 biological replicates (independent cultures). Total RNA was extracted using a hot phenol-chloroform method. cDNA synthesis, fragmentation and labeling, and washing and scanning of E. coli GeneChip Arrays were performed according to the instructions of the manufacturer (Affymetrix Technical Manual, Affymetrix, Inc., USA). Labeled cDNA was hybridized to E. coli Genome 2 Array (Affymetrix, Inc.). Independent array hybridizations were carried out for 3 biological replicates (independent cultures) of each condition. A number of genes in the SoxRS and OxyR oxidative stress regulons were up-regulated by high osmolarity, high temperature, and/or by the combination of both stresses. This result could account for cross-protection of osmotic stress against oxidative stress. The trehalose biosynthetic genes were induced by both stresses, in accord with the proposed protective role of this disaccharide against thermal and oxidative damage. Experiment Overall Design: E. coli K12 strain NCM3722 cultures were grown with aeration in K medium containing 10 or 20 mM glucose. To impose osmotic stress, the osmolarity of the medium was increased to 0.64 osm by supplementation with 0.3 M NaCl. Because E. coli is a methionine auxotroph above 42oC the K medium cultures were supplemented with 0.5 mM methionine. Glycine betaine (GB) was added to the high osmolarity media to a final concentration of 1 mM. Cells taken from a single colony on LB agar were inoculated into 1ml liquid LB and grown to saturation at 37oC, then 0.05 ml were inoculated into i) K medium, 0.5 mM methionine, 10 mM glucose; ii) K medium, 0.5 mM methionine, 10 mM glucose, 0.3 M NaCl; and iii) K medium, 0.5 mM methionine, 10 mM glucose, 0.3 M NaCl, 1 mM GB. The cultures were grown to saturation at 30oC and 43oC, and sub-cultured once into the same medium and grown at the same temperatures as before. Exponentially growing cells form these cultures were then inoculated into Erlenmeyer flasks (starting OD600nm 0.05) containing 40 ml of the same medium, and incubated in the same salt and temperature conditions as used previously, except that the glucose concentration was increased to 20 mM. When the cells reached OD600nm of 0.4-0.5 (~3 doublings), 25 ml were added to a 2.5 ml mixture of cold 95% ethanol and 5% phenol to preserve RNA. The cells were cooled briefly on ice, immediately harvested by centrifugation (4oC), and the pellet was frozen on dry ice. The six different growth conditions used were: C1 - 30oC, no NaCl; C2: 30oC, 0.3 M NaCl; C3: 30oC, 0.3 M NaCl, 1 mM GB; C4: 43oC, no NaCl; C5: 43oC, 0.3 M NaCl; C6: 43oC, 0.3 M NaCl, 1 mM GB.
2009-01-14 | E-GEOD-7656 | biostudies-arrayexpress
Project description:Genome-wide gene expression analysis was performed with the cells in exponential and stationary growth phases. Through these two growth status, 89.6% of currently annotated genes were expressed. High-density oligonucleotide tiling arrays consisting of 379,528 50-mer probes spaced 30 bp apart across the whole Klebsiella pneumoniae MGH 78578 genome was used (Roche NimbleGen).
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Project description:Pseudomonas syringae uses two-component system RhpRS to regulate the expression of type III secretion system (T3SS) genes and bacterial virulence. However, the molecular mechanism and the regulons of RhpRS have yet to be fully elucidated. Here we show that RhpS functions as an autokinase, an RhpR kinase, and a P-RhpR phosphatase. RhpR can also be phosphorylated by small phosphodonor acetyl phosphate. A specific RhpR-binding site containing an inverted repeat (IR) motif GTATC-N6-GATAC, was mapped to its own promoter by DNase I footprint analysis. Electrophoretic mobility shift assay (EMSA) indicated that P-RhpR has higher binding activity than RhpR to the IR motif. To identify additional targets of RhpR in P. syringae, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq), which detected 167 enriched loci including the hrpR promoter, indicating the direct regulation of T3SS cascade genes by RhpR. Genome-wide microarray analysis showed that, besides the T3SS cascade genes, RhpR differentially regulates a large set of genes of various functions in response to different growth conditions. Together, these results suggested that RhpRS is a global regulator that allows P. syringae to sense and respond to environmental changes to coordinate the T3SS and many other biological processes. ChIP-seq analysis of RhpR
2014-10-01 | E-GEOD-58533 | biostudies-arrayexpress
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2012-12-31 | E-GEOD-36055 | biostudies-arrayexpress
Project description:Malic enzymes decarboxylate the tricarboxylic acid (TCA) cycle intermediate malate to the glycolytic end-product pyruvate and are well positioned to regulate metabolic flux in central carbon metabolism. The bacterium Sinorhizobium meliloti has a NAD(P)-malic enzyme (DME) and a NADP-malic enzyme (TME) and DME is required for symbiotic N2-fixation. To help understand the role of these enzymes, we examined growth, metabolic and transcriptional consequences resulting from the deletion of these enzymes. Few effects were observed upon growth with glucose, whereas growth with the gluconeogenic substrate, succinate, resulted in transcriptional and metabolic effects particularly in the dme mutant strains. When grown with succinate, DME mutant cells accumulated hexose sugar phosphates and trehalose, while TME mutants accumulated putrescine. Succinate-grown DME mutant cells also showed increased transcription of genes for gluconeogenesis and for pathways such as amino acid and fatty acid synthesis that divert metabolites away from the TCA cycle. These data suggested that, DME is required to regulate the levels of TCA cycle intermediates and that the activity of TME is insufficient to prevent the accumulation of TCA cycle intermediates in cells utilizing succinate as carbon source. Consistent with this, in short-1-3 hour incubations with succinate, dme mutant cells excreted large amounts of malate whereas little malate was excreted from tme or wild-type cells. These results support the suggestion that DME is required for N2-fixation in alfalfa because it is required for synthesis of pyruvate and acetyl-CoA and the rapid metabolism of C4-dicarboxylates supplied by the plant. RNA expression was measured for S. meliloti in exponential phase grown in MOPS (morpholinpropanesulfonic acid) buffered minimal media under 2 growth conditions: 1) 15 mM succinate, 2) 15 mM glucose; using wild type cells as well as dme and tme mutant strains (6 experiments, 2 replicates: total 12 samples)
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Project description:IrrE is a unique gene in Deinococcus, which is the switch of DNA repair and celluar surival network. Expressing IrrE enhanced the salt tolence in E. coli. To understand the effect of IrrE to E. coli during salt shock, we constructed the IrrE-expressing plasmid pMG1-IrrE. And pMG1 is the empty vector used as a control. The GroESL promoter was amplified from D. radiodurans R1 genomic DNA by PCR with proper primers. The PCR product was ligated into the T-cloning site of T-vector pMD18T, generating the plasmid pMG1. RNA extracted from cells of E. coli K-12 JM109 cells with pMG1 after 4 h of growth to OD 600 achieve 0.4, or cells with pMG1 after 1mol/L NaCl shock for 10 min (and 60 min) when their OD600 achieved 0.4. RNA extracted from cells of E. coli K-12 JM109 cells with pMG1-IrrE after 4 h of growth to OD 600 achieve 0.4, or cells with pMG1-IrrE after 1mol/L NaCl shock for 10 min (and 60 min)when their OD600 achieved 0.4. pMG1 and pMG1-IrrE datasets normalized separately.
2010-07-29 | E-GEOD-17465 | biostudies-arrayexpress
Project description:Glyphosate (GLY) is an effective antimetabolite that acts against the shikimate pathway 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase, However, little is known about the genome-scale transcriptional responses of bacteria after glyphosate shock. To investigate further the mechanisms by which E. coli response to a glyphosate shock, a DNA-based microarray was used for transcriptional analysis of E. coli exposed to 200 mM glyphosate. RNA extracted from cells of E. coli K-12 JM109 cells after 4 h of growth to OD600 achieve 0.4, or cells after 200 mM glyphosate shock for 1 h when their OD600 achieved 0.4.
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