Project description:Analysis of size selected RNA samples to identify sRNAs using wild-type and rpoS mutant strains. Four experiments, two from each of two strains using two protocols.
Project description:RpoS, an alternative sigma factor, is critical for stress response in Escherichia coli.RpoS also acts as a global regulator for stress control of gene expression, and actually dose so in log stage and stationary stage. To further understand the effect of environmental stresses on in ethanologenic strains, DNA microarrys was used to analyze the expression profiles of E. coli and its rpoS mutant strain. BW25113(rpoS-)and BW25113 were selected at log stages and stationary stage of early development for RNA extraction and hybridization on Affymetrix microarrays. To that end, we hand-selected BW25113 and BW25113(rpoS-) according at different treatments: BW25113(rpoS-)at log stage (BW25113(rpoS-) log), BW25113 at log stage (BW25113 log),BW25113(rpoS-)atstationary stage ( BW25113(rpoS-) stationary), BW25113 at stationary stage ( BW25113 stationary)
Project description:The RpoS sigma factor protein of Escherichia coli is the master transcriptional regulator of physiological responses to a variety of stresses. This stress response comes at the expense of scavenging for scarce resources, causing a trade-off between stress tolerance and nutrient acquisition. This trade-off favors non-functional rpoS alleles in nutrient-poor environments. We used experimental evolution to explore how natural selection modifies the regulatory network of strains lacking RpoS when they are evolved in an osmotically stressful environment. We found that strains lacking RpoS adapt less variably, in terms of both fitness increase and changes in patterns of transcription, than strains with functional RpoS. This phenotypic uniformity was caused by the same adaptive mutation in every independent population: the insertion of IS10 into the promoter of otsBA. OtsA and OtsB are required to synthesize the osmoprotectant trehalose, and transcription of otsBA requires RpoS in the wild-type genetic background. The evolved IS10 insertion rewires expression of otsBA from RpoS-dependent to RpoS-independent, allowing for partial restoration of wild-type response to osmotic stress. Our results show that the regulatory networks of bacteria Keywords: evolution; expression
Project description:Transcriptome analysis of two independently derived hns mutants compared to an isogenic wild-type Salmonella (strain 14028s - lab ID# WN153). Note: both the wild-type and hns strains carry an additional mutation in the rpoS locus (encoding the stationary phase sigma factor) resulting in a deletion of amino acids 61-65 that diminish its activity. Keywords: cell type comparison
Project description:The role of rpoS gene in the formation of Escherichia coli biofilms were investigated. The gene expression was compared among E. coli MG1655 wild type strain and rpoS knock-out strain in the biofilms, the planktonic exponential phase, and the planktonic stationary phase. The analysis revealed that the wild type bilfilms (WBF) showed similar pattern of gene expression with the WT planktonic stationary phase (WS), whereas the rpoS knock-out biofilms (MBF) showed similar pattern of gene expression with the wild type planktonic exponential phase (WE). Genes involved in the energy metabolism and the flagella synthesis showed higher expression in the rpoS knock-out biofilms (MBF), but not in the wild type biofilms (WBF). Moreover, genes involved in the stress responses showed higher expression in the wild type biofilms (WBF), but not in the rpoS knock-out biofilms (MBF). Keywords: cell type comparison (biofilms vs planktonic cells, wild type vs rpoS knock-out strains)
Project description:This study is to identify the RpoS regulon in MG1655 in early exponential growth. RNA samples from wild type or rpoS mutants were extracted using acidic hot phenol method and hybridized to Affymetrix E. coli Antisense Genome Array. Keywords: Define regulon of RpoS
Project description:The function and mode of action of small regulatory RNAs is currently still understudied in archaea. In the halophilic archaeon H. volcanii a plethora of sRNAs have been identified, however, in-depth functional analysis is missing for most of them. We selected a small RNA (s479) from H. volcanii for detailed characterization. The sRNA gene is encoded between a CRISPR RNA locus and the Cas protein gene cluster, the s479 deletion strain is viable and was characterized in detail. Transcriptome studies of wild type Haloferax cells and the deletion mutant revealed up-regulation of six genes in the deletion strain, showing that the sRNA has a distinct cellular function. Proteome comparison of wild type and deletion strains further expanded the regulon of s479 deeply rooting this sRNA within the metabolism of H. volcanii especially the regulation of transporter abundance.
Project description:Transcriptional profiling of L. pneumophila JR32 (wild-type) and rpoS- (LM1376) strains grown to stat phase compared to cultures grown to log phase Keywords: growth phase
Project description:The RpoS sigma factor protein of Escherichia coli is the master transcriptional regulator of physiological responses to a variety of stresses. This stress response comes at the expense of scavenging for scarce resources, causing a trade-off between stress tolerance and nutrient acquisition. This trade-off favors non-functional rpoS alleles in nutrient-poor environments. We used experimental evolution to explore how natural selection modifies the regulatory network of strains lacking RpoS when they are evolved in an osmotically stressful environment. We found that strains lacking RpoS adapt less variably, in terms of both fitness increase and changes in patterns of transcription, than strains with functional RpoS. This phenotypic uniformity was caused by the same adaptive mutation in every independent population: the insertion of IS10 into the promoter of otsBA. OtsA and OtsB are required to synthesize the osmoprotectant trehalose, and transcription of otsBA requires RpoS in the wild-type genetic background. The evolved IS10 insertion rewires expression of otsBA from RpoS-dependent to RpoS-independent, allowing for partial restoration of wild-type response to osmotic stress. Our results show that the regulatory networks of bacteria Keywords: evolution; expression This study started with wild-type and rpoS- strains, and evolved five lines from each, for a total of 12 strains. Expression was measured for each strain with two separate biological replicates of RNA
Project description:A fliZ mutant in the entomopathogenic bacterium X. nematophila is attenuated in virulence in the insect. The goal of this study is to compare transcriptomes of the fliZ mutant and wild type strain to identify the FliZ regulon.