Project description:Wild-type E. coli are prototrophic for all amino acid and nucleotides. These are synthesized by a network of interconnected metabolic pathways from a handful precursors molecules, which are regulated at the level of gene expression. It was hypothesized in this study, that since metabolic pathways are interconnected, transcriptional regulation should be shared across multiple pathways. To uncover these regulatory interactions, cells growing at steady state were perturbed by the addition of an end-metabolite (aa or nt), and were allowed to recover. The adjustments in biochemical pathways to the perturbation were sampled by profiling mRNA abundance 10 minutes after the perturbation. By limiting the scope and magnitude of the perturbation, mRNA changes are expected to be limited to specific responses to the perturbation and not genome-wide changes associated with larger perturbations such as nutritional shifts and stresses.
Project description:We measured the mRNA abundance in E.coli using RNAseq to calculate mRNA lifetimes. The data is used in support of a larger paper on the proteome and transcriptome of E.coli.
Project description:MgrR is a newly characterized Hfq dependent small RNA RNA. The expression of MgrR is regulated by Two component system, PhoPQ regulon, which senses low Mg2+ in environment. It has been reported that Hfq-binding sRNAs base pair with target RNAs, frequently leading to rapid degradation of target messages or, less frequently, to stabilization, both of which can be assayed by using microarrays. In order to search for the target genes of MgrR, we therefore examined the consequences of MgrR expression on mRNA abundance under two conditions. In condition 1, the chromosomal copy of mgrR was deleted and MgrR was expressed for 15’ from an induced plac-mgrR plasmid and compared to cells carrying a vector induced for the same period. In condition 2, the expression of mRNAs was compared in wild-type cells (mgrR+) and the mgrR deletion strain, both grown in LB; because MgrR levels are fairly high under our normal growth conditions, this allowed analysis of both the direct and indirect (long-term) effects of MgrR.
Project description:We measured the mRNA abundance in E.coli using RNAseq to calculate mRNA lifetimes. The data is used in support of a larger paper on the proteome and transcriptome of E.coli. Comparison of mRNA abundance over time, after the addition of transcription inhibitor, rifampicin. Center: Harvard University
Project description:The goal of this study is to compare gene expression data for a well known model organism (Escherichia coli) using different technologies (NGS here, microarray from GSE48776). mRNA profiles of Wild Type and two Mutant Strains (ydcR (b1439) MUTANT and yjiR (b4340) MUTANT), growth in minimal medium, were generated by deep sequencing, in triplicate, using Illumina MiSeq.
Project description:Abstract: Much of the information available about factors that affect mRNA decay in Escherichia coli, and by inference in other bacteria, has been gleaned from study of less than 25 of the approximately 4,300 predicted E. coli messages. To investigate these factors more broadly, we examined the half-lives and steady-state abundance of known and predicted E. coli mRNAs at single-gene resolution by using two-color fluorescent DNA microarrays. An rRNA-based strategy for normalization of microarray data was developed to permit quantitation of mRNA decay after transcriptional arrest by rifampicin. We found that globally, mRNA half-lives were similar in nutrient-rich media and defined media in which the generation time was approximately tripled. A wide range of stabilities was observed for individual mRNAs of E. coli, although approximately 80% of all mRNAs had half-lives between 3 and 8 min. Genes having biologically related metabolic functions were commonly observed to have similar stabilities. Whereas the half-lives of a limited number of mRNAs correlated positively with their abundance, we found that overall, increased mRNA stability is not predictive of increased abundance. Neither the density of putative sites of cleavage by RNase E, which is believed to initiate mRNA decay in E. coli, nor the free energy of folding of 5' or 3' untranslated region sequences was predictive of mRNA half-life. Our results identify previously unsuspected features of mRNA decay at a global level and also indicate that generalizations about decay derived from the study of individual gene transcripts may have limited applicability. This SuperSeries is composed of the SubSeries listed below.
Project description:The aim of the study was to compare the transcriptome of E. coli K12 MG1655 cells lacking hydroperoxidase (Hpx-) and therefore unable to detoxify hydrogen peroxide, to wild-type cells; both when the Rtc RNA repair system is active and when it is inhibited; at 8 and 24 hpi. A very large number of genes (up to 1/3) were found to be differentially expressed in Hpx- as compared to wild-type. Inhibition of the Rtc system had dramatic effects on Hpx- but not on wild-type.