Effect of cortisol on S. Typhimurium parental strain and an isogenic scsA mutant
Ontology highlight
ABSTRACT:
ORGANISM(S): Salmonella enterica subsp. enterica serovar Typhimurium
SUBMITTER: Arthur Thompson
PROVIDER: E-GEOD-55430 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:The expression profile of an S. Typhimurium hfq mutant-strain was compared to the parental strain under 2 different growth conditions; early stationary phase and SPI-1 (Salmonella pathogenicity island 1) inducing condition. Keywords: Genetic modification This study comprises two separate experiments performed under different growth conditions, were the gene expression profile was compared to that of the parental strain. Three biological replicates were performed for each strain and condition. For this study, we used Salmonella genomic DNA as the comparator which also acted as the control for spot quality.
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2011-07-25 | E-GEOD-30923 | biostudies-arrayexpress
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2013-07-03 | E-GEOD-48478 | biostudies-arrayexpress
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2010-06-11 | E-GEOD-4631 | biostudies-arrayexpress
Project description:It is well established that small noncoding RNAs (sRNAs) of bacteria recognize the 5â?? regions of target mRNAs, generally at the ribosome binding site. Until now, the translated coding sequence (CDS) of mRNA appeared to be refractory to sRNA interactions. We have discovered that Salmonella MicC RNA silences ompD mRNA by targeting the CDS, at codons 23-26. Analyses of MicC-ompD RNA complexes in vitro, and of chimeric sRNAs and ompD reporter fusions in vivo, show that interactions are confined to the CDS, and that a â?¤12 bp RNA duplex involving the conserved 5â?? end of MicC is essential and sufficient for target repression. MicC cannot act as a translational repressor at this downstream position being unable to inhibit 30S or 70S ribosome activity on the ompD mRNA. Instead, MicC accelerates RNase E-dependent ompD mRNA decay. The degradosome contributes to target destabilization, and facilitates the efficient degradation of processed ompD mRNA. Our data show that bacterial gene silencing by sRNAs can take place downstream of the translational initiation site by triggering irreversible mRNA decay. This ability of sRNAs allows targets in the CDS to be silenced without interference from the strong RNA helicase activity of elongating ribosomes. To determine the targets of the small regulatory RNA MicC in S. Typhimurium, we looked at the effect of a short pulse of MicC over-expression on the Salmonella transcriptome. To achieve over-expression, the micC gene was cloned in the pBAD plasmid and induced with 0.2% L-arabinose for 10 min. We then extracted the total RNA for transcriptional profiling. A strain carrying the pBAD plasmid w/o insert was used as negative control. 3 biological replicates were performed. This sRNA target identification strategy has been described in Papenfort et al; Molecular Microbiology (2006) 62(6), 1674â??1688.
2010-05-16 | E-GEOD-16540 | biostudies-arrayexpress
Project description:StpA is a paralogue of the nucleoid associated protein H-NS that is conserved in a range of enteric bacteria and had no known function in Salmonella enterica serovar Typhimurium. Here, we show that 5% of the Salmonella genome is regulated by StpA, which contrasts with the situation in Escherichia coli where deletion of stpA only had minor effects on gene expression. The StpA-dependent genes of S. Typhimurium are a specific subset of the H-NS regulon that are predominantly under the positive control of sigma38 (RpoS), CRP-cAMP and PhoP. The regulatory role of StpA varied at different growth phases; StpA only controlled sigma38 levels at mid-exponential phase when it prevented inappropriate activation of sigma38 during rapid bacterial growth. In contrast, StpA only activated the CRP-cAMP regulon during late exponential phase. To test the hypothesis that stpA prevents Sigma38-dependent transcription during mid-exponential growth in S. Typhimurium, we analysed the effect of the stpA deletion on transcription in the presence and absence of rpoS. Three biological replicates were performed for each strain. For this study, we used Salmonella genomic DNA as the comparator which also acted as the control for spot quality.
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Project description:The small RNA, ArcZ (previously RyhA/SraH), was discovered in several genome-wide screens in Escherichia coli and Salmonella. Its high degree of genomic conservation, its frequent recovery by shotgun sequencing, and its association with the RNA chaperone, Hfq, identified ArcZ as an abundant enterobacterial âcoreâ small RNA of unknown function. Here, we report that ArcZ acts as a post-transcriptional regulator in Salmonella, repressing the mRNAs of the widely distributed sdaCB (serine uptake) and tpx (oxidative stress) genes, and of STM3216, a horizontally acquired methyl-accepting chemotaxis protein (MCP). Both sdaCB and STM3216 are regulated by sequestration of the ribosome binding site. In contrast, the tpx mRNA is targeted in the coding sequence (CDS), arguing that CDS targeting is more common than appreciated. Transcriptomic analysis of an arcZ deletion strain further argued for the existence of a distinct set of Salmonella loci specifically regulated by ArcZ. In contrast, increased expression of the sRNA altered the steady-state levels of >16% (â¥750) of all Salmonella mRNAs, and rendered the bacteria non-motile. Deep sequencing detected a dramatically changed profile of Hfq-bound sRNAs and mRNAs suggesting that the unprecedented degree of pleiotropic regulation might in part be caused by titration of Hfq binding by ArcZ. This study used three different approaches to identify target genes and biological role of the small RNA ArcZ in Salmonella Typhimurium. Transcriptomic analysis of ArcZ overexpression: Strain JVS-0082 (ÎarcZ) was transformed with plasmids pJV300 (control) and pKP48-1 (parcZ), and grown in liquid culture (LB broth) inoculated 1:100 from an overnight culture for 6h after cells had reached an OD600=2.0 to attain late stationary phase. Transcriptomic analysis of arcZ mutant strain: Strains JVS-007 (WT) and JVS-0082 (ÎarcZ) were transformed with plasmid pJV300 (control) and grown in liquid culture (LB broth) inoculated 1:100 from an overnight culture for 6h after cells had reached an OD600=2.0 to attain late stationary phase. Transcriptional effects of ArcZ pulse expression: Strain SL1344 was transformed with plasmids pKP8-35 (pBAD-control) and pKP4-13 (pBAD-ArcZ), and grown in liquid culture (LB broth) inoculated 1:100 from an overnight culture to an OD600 of 1.5. Expression of the insert was induced with L-arabinose (0.2% final concentrations) for 10 min. Three biological replicates were performed for each strain/condition.
2009-10-19 | E-GEOD-17771 | biostudies-arrayexpress
Project description:StpA is a paralogue of the nucleoid associated protein H-NS that is conserved in a range of enteric bacteria and had no known function in Salmonella enterica serovar Typhimurium. Here, we show that 5% of the Salmonella genome is regulated by StpA, which contrasts with the situation in Escherichia coli where deletion of stpA only had minor effects on gene expression. The StpA-dependent genes of S. Typhimurium are a specific subset of the H-NS regulon that are predominantly under the positive control of sigma38 (RpoS), CRP-cAMP and PhoP. The regulatory role of StpA varied at different growth phases; StpA only controlled sigma38 levels at mid-exponential phase when it prevented inappropriate activation of sigma38 during rapid bacterial growth. In contrast, StpA only activated the CRP-cAMP regulon during late exponential phase. The effect of stpA deletion on S. Typhimurium gene expression during growth in LB was analysed at 4 different time points (early-log, mid-log, late-log, and stationary phase) where the gene expression profile of the stpA-deletion strain was compared to that of the parental strain. Between two and three biological replicates were performed for each strain and time point. For this study, we used Salmonella genomic DNA as the comparator which also acted as the control for spot quality.
2009-10-27 | E-GEOD-18424 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE18424: The effect of stpA deletion on S. Typhimurium gene expression during growth in rich medium GSE18428: StpA prevents RpoS-dependent transcription during mid-exponential growth in S. Typhimurium GSE18450: Identification of StpA-binding sites on the Salmonella genome Refer to individual Series
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