Project description:To understand the mechanism of isopropanol tolerance of Escherichia coli for improvement of isopropanol production, we performed genome re-sequencing and transcriptome analysis of isopropanol tolerant E. coli strains obtained from parallel adaptive laboratory evolution under IPA stress.
2017-06-21 | GSE89685 | GEO
Project description:Escherichia coli transcriptome of acid-adapted strains evolved under pH 5.5
Project description:The effect of an extracellular acid shift on gene expression profiles of Escherichia coli K-12 W3110 was observed using Affymetrix E. coli arrays. In order to maximize aeration and maintain logarithmic growth, the overnight culture (LBK broth medium) was diluted 500-fold into a 250-ml baffled flask containing 55 ml of 20mM HOMOPIPES buffered medium (pH 7.6). Cultures were grown to OD600=0.2. A shift to acid external pH was conducted by rapid addition of 840 µl 1M HCl, which lowered the pH of the medium to pH 5.5. For each of five biological replicates, 10-ml samples were taken at times 0, 1, 5, and 10 min post addition of HCl. Each sample was added to 1 ml 10% phenol-ethanol stop solution in <5 sec. For each sample, cDNA synthesized from total RNA was hybridized onto Affymetrix E. coli arrays. Model-based gene expression intensities were determined using GCOS software. Gene-by-gene temporal differential expression was analyzed as a mixed-effects model using polynomial time functions as fixed effects and flask variation as a random effect. Experiment Overall Design: Gene expression profiles of Escherichia coli K-12 W3110 were compared as a function of time versus change in external pH. Overnight cultures were diluted 1:500 in potassium-modified Luria-Bertani medium (LBK) buffered with 20 mM HOMOPIPES at 7.6. Bacteria were cultured in baffled flasks (less than 10% volume) with rotation at 225 rpm, incubated at 37°C to an optical density at 600 nm of 0.2. External pH was lowered to pH 5.5 by adding 840 µl of 1M HCl to 40 mls of culture within 5 seconds. Four samples were taken from each of five replicate cultures, corresponding to time 0 (before HCl addition),1, 5, and 10 min post HCl addition.
Project description:The response to acid stress is a fundamental process in bacteria. Three transcription factors, GadE, GadW, and GadX (GadEWX) are known to play a critical role in the transcriptional regulation of glutamate-dependent acid resistance (GDAR) system in Escherichia coli K-12 MG1655. However, the regulatory role of GadEWX in coordinating interacting cellular functions is still unknown. Here, we comprehensively reconstruct genome-wide GadEWX transcriptional regulatory network in E. coli K-12 MG1655 under acidic stress. Integrative data analysis reveals that GadEWX regulons are comprised of 45 genes in 31 transcription units (TUs), significantly expanding the current knowledge of the GadEWX regulatory network. We demonstrate that GadEWX directly and coherently regulate several proton efflux/influx and generating/consuming enzymes with pairs of negative-feedback loops to maintain pH homeostasis by controlling proton flow. In addition, GadEWX regulate genes with assorted functions including molecular chaperones, acid resistance, stress response, and other regulatory activities. These results present a comprehensive understating on how GadEWX simultaneously coordinates many other cellular processes to produce the overall response of E. coli to acid stress. A total of six samples were analyzed. GadE-8-myc, GadW-8 -myc, and GadX-8-myc tagged cells were cultured in M9 glucose minimal media at pH 5.5 with biological duplicates.
Project description:I-motifs (iMs) are four-stranded non-B DNA structures containing C-rich DNA sequences, which can be formed under various pH conditions. DNA methylation exhibits complex impacts on iM formation in vitro. However, how DNA methylation differentially affects pH dependent iM formation on a genome wide scale is completely uncharacterized in both humans and plants. To this end, we conducted iM-IP-seq under pH 5.5 and 7.0 conditions using CK and hyper/hypomethylated DNA in combination with BS-seq in rice. We found that pH 7.0 and 5.5 biased iMs had distinct genomic features and differential DNA methylation levels, the former having higher DNA methylation levels than the latter. Moreover, DNA demethylation and hyper methylation had more impacts on a subset of iM formation under pH 7.0 and 5.5, respectively, indicating that DNA de/hyper-methylation exhibits pH dependent impacts on iM formation. Importantly, we found that CG hypo-DMRs and CHH hyper-DMRs alone or coordinated with CG/CHG hyper-DMRs may play determinant roles in the regulation of iM formation under pH 5.5 and 7.0. Thus, our study shows that intrinsic DNA sequences alone or in combination with DNA methylation play vital roles in determining pH-dependent formation of iMs. It will contribute to in-depth understanding of DNA methylation in the modulation of pH dependent dynamics of iM conformation, therefore broadening its biological implications and practical application ranges.
Project description:Two genetic selection systems that couple metabolite hydroxylation or methylation of small molecules to growth of Escherichia coli are presented in this study. One system targets pterin-dependent hydroxylation (tBPt) while another focuses on S-adenosylmethionine-dependent methylation (SAM). Using adaptive laboratory evolution with growth selection, these two systems are demonstrated to not only achieve in vivo directed evolution of enzymes involved in human hormone biosynthesis but also reveal non-intuitive host factors that elude existing synthetic biology approaches. Raw sequencing data for the relevant strains generated in this study are presented here.
Project description:The effect of an extracellular acid shift on gene expression profiles of Escherichia coli K-12 W3110 was observed using Affymetrix E. coli arrays. In order to maximize aeration and maintain logarithmic growth, the overnight culture (LBK broth medium) was diluted 500-fold into a 250-ml baffled flask containing 55 ml of 20mM HOMOPIPES buffered medium (pH 7.6). Cultures were grown to OD600=0.2. A shift to acid external pH was conducted by rapid addition of 840 µl 1M HCl, which lowered the pH of the medium to pH 5.5. For each of five biological replicates, 10-ml samples were taken at times 0, 1, 5, and 10 min post addition of HCl. Each sample was added to 1 ml 10% phenol-ethanol stop solution in <5 sec. For each sample, cDNA synthesized from total RNA was hybridized onto Affymetrix E. coli arrays. Model-based gene expression intensities were determined using GCOS software. Gene-by-gene temporal differential expression was analyzed as a mixed-effects model using polynomial time functions as fixed effects and flask variation as a random effect. Keywords: Time Course
Project description:OmpR is a DNA binding protein belonging to the OmpR/EnvZ two component system. This system is known to sense changes in osmolarity in Escherichia coli. Recently, OmpR in Salmonella enterica serovar Typhimurium was found to be activated by acidic pH and DNA relaxation. In this study, ChIP-on-chip was employed to ascertain the genome-wide distribution of OmpR in Salmonella Typhimurium and Escherichia coli in acidic and neutral pH. In addition we investigated the affect of DNA relaxation on OmpR binding in Salmonella Typhimurium.
Project description:Using a synthetic biosensor to couple production of a specific metabolite with cell growth, we spontaneously evolved cells under the selective condition toward the acquisition of genotypes that optimally reallocated cellular resources. Using 3-hydroxypropionic acid (3-HP) production from glycerol in Escherichia coli as a model system, we determined that spontaneous mutations in the conserved regions of proteins involved in global transcriptional regulation altered the expression of several genes associated with central carbon metabolism. Our study provides a new perspective on adaptive laboratory evolution (ALE) using synthetic biosensors, thereby supporting future efforts in metabolic pathway optimization.
Project description:Relative quantification of protein abundances of three yeast strains (Saccharomyces cerevisiae CEN.PK113-7D, Kluyveromyces marxianus CBS6556 and Yarrowia lipolytica W29) cultivate in chemostats under different conditions. The conditions for Saccharomyces cerevisiae CEN.PK113-7D are: - Standard condition – 30°C, pH 5.5 - High temperature - 36°C, pH 5.5 - Low pH - 30°C, pH 3.5 - Osmotic stress – 30°C, pH 5.5, 1M KCl The conditions for Kluyveromyces marxianus CBS6556 are: - Standard condition – 30°C, pH 5.5 - High temperature - 40°C, pH 5.5 - Low pH - 30°C, pH 3.5 - Osmotic stress – 30°C, pH 5.5, 0.6 M KCl The conditions for Yarrowia lipolytica W29 are: - Standard condition - 28°C, pH 5.5 - High temperature - 32°C, pH 5.5 - Low pH - 28°C, pH 3.5 This study is part of the OMICS data generation of CHASSY project (European Union’s Horizon 2020 grant agreement No 720824).