Project description:This study is an analysis of changes in gene expression during stringent response in Vibrio cholerae. V. cholerae cells in mid-log were treated with serine hydroxamate and gene expression was compared to untreated cells. Keywords: Stress response, stringent response
Project description:The stringent response was defined in Lactococcus lactis through transcript profiling after the addition of a chemical inductor, the norvaline. Gene expression was measured in the exponential growth phase (reference sample) and at 1.6 h after norvaline addition. Four hundred and sixty one differentially expressed genes were identified and constituted the stringent response regulon. Keywords: stress response, time course
Project description:The stringent response was defined in Lactococcus lactis through transcript profiling after the addition of a chemical inductor, the norvaline. Gene expression was measured in the exponential growth phase (reference sample) and at 1.6 h after norvaline addition. Four hundred and sixty one differentially expressed genes were identified and constituted the stringent response regulon. Keywords: stress response, time course Stringent response was imposed through norvaline addition during the growth of Lactococcus lactis IL1403 under controlled conditions (30 °C, pH 6.6, nitrogen atmosphere). Cell samples were harvested in exponential phase and 1.6 h after norvaline addition. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 2053 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. The 2 time-points were analyzed simultaneously and 3 independent repetitions were performed.
Project description:Transcriptome analysis of Streptococcus agalactiae (group B Streptococcus) grown under control conditions or coincubated with serine hydroxamate to induce the bacterial stringent response
Project description:The stringent response is an adaptive physiological response triggered by different conditions of nutritional or environmental stress and aimed at increasing survival under harsh conditions. This response is mediated the signalling nucleotides guanosine tetraphosphate (ppGpp) and pentaphospate (pppGpp), collectively known as (p)ppGpp. In this study we aim to identify genome-wide targets of regulation by the stringent-response associated alarmone (p)ppGpp in Pseudomonas putida by performing RNA-seq experiments using the wild-type KT2440tel strain and a KT2440tel-derivative bearing deletions of the (p)ppGpp synthetase-encoding genes relA and spoT (ppGpp0 mutant).
Project description:Sinorhizobium meliloti is a soil-dwelling symbiotic alphaproteobacterium. Cyclic di-GMP is an important second messenger controlling multiple functions in this microorganism. To understand transcriptional regulation by elevated c-di-GMP in S. meliloti, the transcriptome analysis was performed on the wild type strain S. meliloti Rm2011 carrying either an empty vector pWBT or diguanylate cyclase gene pleD overexpression plasmid pWBT-pleD.
Project description:Sinorhizobium meliloti lives as a soil saprophyte, and engages in a nitrogen fixing symbiosis with plant roots. To succeed in such diverse environments, the bacteria must continually adjust gene expression. Transcriptional plasticity in eubacteria is often mediated by alternative sigma factors interacting with core RNA polymerase. The S. meliloti genome encodes 14 of these alternative sigmas, including 11 extracytoplasmic function (ECF) sigmas. We used custom Affymetrix Symbiosis Chips to characterize the global transcriptional response of S. meliloti overexpressing the ECF sigma factor, RpoE2. Our work identifies over 200 genes whose expression is dependent on RpoE2.
Project description:Bacteria respond to nutrient starvation implementing the stringent response, a stress signalling system resulting in metabolic remodelling leading to decreased growth rate and energy requirements. A well-characterized model of stringent response in Mycobacterium tuberculosis is that one induced by growth in low phosphate. The extracytoplasmic function (ECF) sigma factor SigE was previously suggested having a key role in the activation of stringent response. In this study we challenge this hypothesis by analyzing the temporal dynamics of the transcriptional response of a sigE mutant and its wild-type parental strain to low phosphate using RNA sequencing. We found that both strains responded to low phosphate with a typical stringent response trait, including the downregulation of genes encoding ribosomal proteins and RNA polymerase. We also observed transcriptional changes that support the occurring of an energetics imbalance, compensated by a reduced activity of the electron transport chain, decreased export of protons and a remodelling of central metabolism. The most striking difference between the two strains was the induction in the sigE mutant of several stress-related genes. In particular, the genes encoding the ECF sigma factor SigH and the transcriptional regulator WhiB6. Since both proteins respond to redox unbalances, their induction suggests that the sigE mutant is not able to maintain redox homeostasis in response to the energetics imbalance induced by low phosphate. In conclusion, our data suggest that SigE is not directly involved in initiating stringent response, but in protecting the cell from stress consequent to the exposure to low phosphate and activation of stringent response.
Project description:Sinorhizobium meliloti can live as a soil saprophyte, and can engage in a nitrogen fixing symbiosis with plant roots. To succeed in such diverse environments, the bacteria must continually adjust gene expression. Transcriptional plasticity in eubacteria is often mediated by alternative sigma factors interacting with core RNA polymerase. The S. meliloti genome encodes 14 of these alternative sigmas, including two putative RpoH (heat shock) sigmas. We used custom Affymetrix Symbiosis Chips to characterize the global transcriptional response of S. meliloti rpoH1, rpoH2 and rpoH1 rpoH2 mutants during heat shock and stationary phase growth. Under these conditions, expression of over 300 genes is dependent on rpoH1 and rpoH2.