Project description:An assortment of genetically engineered Escherichia coli strains of the rewired gene regulation were used to study whether the cells could adapt to the environmental changes without the evolved gene regulatory machinaries. These E. coli strains had a synthetic gene circuit comprising a rewried gene that natively located within the His opeon. The cells growing under histidine supplied or depleted conditions were subjected to the macrioarray analysis. Multilevel analyses were performed to evaluate the global reorganization of gene expression in response to histidine depletion. A common pattern in transcriptome was observed in the adpative cells, indicating a survival strategy of "stochastic adaptation with regular transcriptome reorganization". The genetically engineered strains of rewired genes and the control strain of the native gene regulation were grown in the presence and absence of histidine, and the cells within the exponetially growing phase were collected for the microarray analysis. Temproal changes in response to histidine depletion were also investigated. Every 3 biological replications for each condition were performed. Total 90 array assays were reported here.
Project description:An assortment of genetically engineered Escherichia coli strains of the rewired gene regulation were used to study whether the cells could adapt to the environmental changes without the evolved gene regulatory machinaries. These E. coli strains had a synthetic gene circuit comprising a rewried gene that natively located within the His opeon. The cells growing under histidine supplied or depleted conditions were subjected to the macrioarray analysis. Multilevel analyses were performed to evaluate the global reorganization of gene expression in response to histidine depletion. A common pattern in transcriptome was observed in the adpative cells, indicating a survival strategy of "stochastic adaptation with regular transcriptome reorganization".
Project description:Stochastic switching of a monostable circuit mediated the adaptation of the engineered OSU12-hisC Escherichia coli strain to histidine starvation. In this strain, the hisC gene was deleted from the His operon and placed under the control of a monostable foreign promoter. In response to histidine depletion, the OSU12-hisC population shifted to a higher HisC expression level, which are beneficial under starving conditions but are not favoured by the monostable circuit. Microarray analysis indicated that OSU12-hisC reorganised its transcriptome to reach the appropriate physiological state upon starvation. The study suggests that bacteria do not necessarily need to evolve signalling mechanisms to control gene expression appropriately, even for essential genes.
Project description:Our laboratory has recently discovered that E. coli cells starved for the DNA precursor dGTP are killed efficiently (dGTP starvation) in a manner similar to that described for Thymineless Death (TLD). Conditions for specific dGTP starvation can be achieved by depriving an E. coli optA1 gpt strain of the purine nucleotide precursor hypoxanthine (Hx). To gain insight into the mechanisms underlying dGTP starvation, we conducted genome-wide gene expression analyses on actively growing optA1 gpt strains subjected to hypoxanthine deprivation for increasing periods of time. The data show that, upon Hx withdrawal, the optA1 gpt strain displays a diminished ability to de-repress the de novo purine biosynthesis genes, and this is likely due to internal guanine accumulation. The impairment to fully induce the purR regulon may be a contributing factor to the lethality of dGTP starvation. At later time points, and coinciding with cell lethality, strong induction of the SOS is observed, supporting the concept of replication stress as a final cause of death. No evidence was observed for the participation of other stress responses, including the rpoS-mediated global stress response in the starved cells, and reinforcing the lack of feedback of replication stress into the global metabolism of the cell. The genome-wide expression data also provide direct evidence for increased genome complexity during dGTP starvation, as a markedly increased gradient is observed for expression of genes located nearby the replication origin relative to those located towards the replication terminus.
Project description:Human Peptidoglycan Recognition Proteins (PGRPs) kill bacteria, likely by over-activating stress responses in bacteria. To gain insight into the mechanism of PGRP killing of Escherichia coli and bacterial defense against PGRP killing, gene expression in E. coli treated with a control protein (bovine serum albumin, BSA), human recombinant PGRP (PGLYRP4), gentamicin (aminoglycoside antibiotic), and CCCP (membrane potential decoupler) were compared. Each treatment induced unique and somewhat overlapping pattern of gene expression. PGRP highly increased expression of genes for oxidative and disulfide stress, detoxification and efflux of Cu, As, and Zn, repair of damaged proteins and DNA, methionine and histidine synthesis, energy generation, and Fe-S clusters repair. PGRP also caused marked decrease in the expression of genes for Fe uptake and motility. Gene expression microarray in E. coli exposed to a human bactericidal innate immunity protein, PGRP, showed induction of oxidative stress response and defense genes, with different expression pattern than E. coli exposed to an aminoglycoside antibiotic and a membrane potential decoupler.
Project description:Investigation of whole genome gene expression level changes in a Escherichia coli MG1655 K-12 ∆arcA mutant, compared to the wild-type strain. The mutations engineered into this strain produce a strain lacking the ArcA protein. The results are further described in the manuscript The response regulator ArcA uses a diverse binding site architechture to globally regulate carbon oxidation in E. coli
Project description:We conducted experimental evolution of E. coli a mutual cross-feeding coculture, composed of two genetically-engineered Escherichia coli populations, I- and L-, which lack genes for biosynthesis of Ile (ilvE gene) and Leu (leuB gene), respectively. These two populations grew in a coculture by complementing required nutrients each other. After 883 generations of evolution experiments, we measured evolutionary changes in transcriptome, and we found ABC transporters for the branched chain amino acids (Ile, Leu, and Val) were significantly increased in both I- and L-. Also, we got other various results that would be interesting to discuss.
Project description:YbjN, an enterobacteria-specific protein, is a multicopy suppressor of ts9 temperature sensitivity in Escherichia coli. Microarray study revealed that the expression level of ybjN was inversely correlated with the expression of flagellar, fimbrial and acid resistance genes. Over-expression of ybjN significantly down-regulated genes involved in the citric acid cycle, glycolysis, the glyoxylate shunt, oxidative phosphorylation, and amino acid and nucleotide metabolism. On the other hand, over-expression of ybjN up-regulated toxin-antitoxin modules, the SOS responsive pathway, cold shock proteins and starvation-induced transporter genes. Our results collectively suggest that YbjN may play important roles in regulating bacterial multicellular behaviors, metabolism and survival under various stress conditions in Es. coli.
Project description:Transcriptional profiling of responses of E. coli thymine auxotrophs to i) growth under sub-optimal thymine concentration (TLM) and ii) lethal conditions under complete thymine starvation (TLD).
Project description:A genome reduced E. coli strain MDS42ΔgalK::Ptet-gfp-kan were applied for the comparative transcriptome analysis. Genome-wide transcriptional changes under high osmotic prresure, high temperature condition and starvation were evaluated.