Escherichia coli
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ABSTRACT:
PROVIDER: PRJNA215332 | ENA |
REPOSITORIES: ENA
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Project description:As part of our studies on the biological functions of polyamines we have used a mutant of Escherichia coli that lacks all the genes for polyamine biosynthesis for a global transcription analysis on the effect of added polyamines. The most striking early response to polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR) that is essential for the survival of bacteria when passing through the acid environment of the stomach. Not only were the two genes for glutamate decarboxylases (gadA and gadB) and the gene for glutamate -γ-aminobutyrate antiporter (gadC) induced by polyamine addition, but also the various genes involved in the regulation of this system were induced. We confirmed the importance of polyamines for the induction of the GDAR system by direct measurement of glutamate decarboxylase activity and acid-survival. Effects of deletions of the regulatory genes in the GDAR system and on the effects of overproduction of two of these genes were also studied. Strikingly, overproductions of the alternate sigma factor rpoS and of the regulatory gene gadE resulted in very high levels of glutamate decarboxylase and almost complete protection against acid stress even in the absence of any polyamines. Thus, these data show that a major function of polyamines in E. coli is protection against acid stress by increasing the synthesis of glutamate decarboxylase, presumably by increasing the levels of the rpoS and gadE regulators. E. coli coltures were treated with PA and PS and its control with three biological replications
2013-12-05 | E-GEOD-49918 | biostudies-arrayexpress
Project description:As part of our studies on the biological functions of polyamines we have used a mutant of Escherichia coli that lacks all the genes for polyamine biosynthesis for a global transcription analysis on the effect of added polyamines. The most striking early response to polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR) that is essential for the survival of bacteria when passing through the acid environment of the stomach. Not only were the two genes for glutamate decarboxylases (gadA and gadB) and the gene for glutamate -γ-aminobutyrate antiporter (gadC) induced by polyamine addition, but also the various genes involved in the regulation of this system were induced. We confirmed the importance of polyamines for the induction of the GDAR system by direct measurement of glutamate decarboxylase activity and acid-survival. Effects of deletions of the regulatory genes in the GDAR system and on the effects of overproduction of two of these genes were also studied. Strikingly, overproductions of the alternate sigma factor rpoS and of the regulatory gene gadE resulted in very high levels of glutamate decarboxylase and almost complete protection against acid stress even in the absence of any polyamines. Thus, these data show that a major function of polyamines in E. coli is protection against acid stress by increasing the synthesis of glutamate decarboxylase, presumably by increasing the levels of the rpoS and gadE regulators.
2013-12-05 | GSE49918 | GEO
Project description:To study the physiological roles of polyamines, we have carried out a global microarray analysis on the effect of adding polyamines to an Escherichia coli mutant that lacks polyamines because of deletions in the genes in the polyamine biosynthetic pathway. Previously, we have reported that the earliest response to the polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR). We also presented preliminary evidence for the involvement of rpoS and gadE regulators. In the current study further confirmation of the regulatory roles of rpoS and gadE is shown by a comparison of genome-wide expression profiling data from a series of microarrays comparing the genes induced by polyamine addition to polyamine-free rpoS+/gadE+ cells with genes induced by polyamine addition to polyamine-free ∆rpoS and ∆gadE cells. The results indicate that most of the genes in the E. coli GDAR system that are induced by polyamines require rpoS and gadE. Our data also show that, gadE is the main regulator of GDAR and other acid-fitness-island genes. Both polyamines and rpoS are necessary for the expression of gadE genes from the three promoters of gadE (P1, P2 and P3). The most important effect of polyamine addition is the very rapid post-transcriptional increase in the level of RpoS sigma factor. Our current hypothesis is that polyamines increase the level of RpoS protein, and that this increased RpoS level is responsible for the stimulation of gadE expression, which in turn induces the GDAR system in E. coli. Three replications for E. coli strains HT874, HT873, HT875, HT873 treated with or no polyamines(PA)
2015-08-06 | E-GEOD-67119 | biostudies-arrayexpress
Project description:To study the physiological roles of polyamines, we have carried out a global microarray analysis on the effect of adding polyamines to an Escherichia coli mutant that lacks polyamines because of deletions in the genes in the polyamine biosynthetic pathway. Previously, we have reported that the earliest response to the polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR). We also presented preliminary evidence for the involvement of rpoS and gadE regulators. In the current study further confirmation of the regulatory roles of rpoS and gadE is shown by a comparison of genome-wide expression profiling data from a series of microarrays comparing the genes induced by polyamine addition to polyamine-free rpoS+/gadE+ cells with genes induced by polyamine addition to polyamine-free ∆rpoS and ∆gadE cells. The results indicate that most of the genes in the E. coli GDAR system that are induced by polyamines require rpoS and gadE. Our data also show that, gadE is the main regulator of GDAR and other acid-fitness-island genes. Both polyamines and rpoS are necessary for the expression of gadE genes from the three promoters of gadE (P1, P2 and P3). The most important effect of polyamine addition is the very rapid post-transcriptional increase in the level of RpoS sigma factor. Our current hypothesis is that polyamines increase the level of RpoS protein, and that this increased RpoS level is responsible for the stimulation of gadE expression, which in turn induces the GDAR system in E. coli.
2015-08-06 | GSE67119 | GEO
Project description:Integrating laterally acquired virulence genes into the backbone regulatory network is important for the pathogenesis of Escherichia coli O157:H7, which has captured many virulence genes through horizontal transfer during evolution. GadE is an essential transcriptional activator of glutamate decarboxylase (GAD) system, the most efficient acid resistance mechanism in E. coli. The full contribution of GadE to the acid resistance and virulence of pathogenic E. coli O157:H7 remains largely unknown. We inactivated gadE in E. coli O157:H7 Sakai and compared global transcription profiles with that of wild type in exponential and stationary phases of growth using microarrays containing 6088 ORFs from three E. coli genomes. gadE inactivation significantly altered the expression of 60 genes independent of growth phase and 122 genes in a growth phase-dependent manner. Inactivation of gadE markedly down-regulated the expression of gadA, gadB, gadC and many acid fitness island genes in a growth phase-dependent manner. Nineteen genes encoded on the locus of enterocyte effacement (LEE), including ler, showed a significant increase in expression upon gadE inactivation. Altogether, our data indicate that GadE is critical for acid resistance of E. coli O157:H7 and plays an important role in virulence by down-regulating expression of LEE.
2008-10-11 | GSE13132 | GEO
Project description:Integrating laterally acquired virulence genes into the backbone regulatory network is important for the pathogenesis of Escherichia coli O157:H7, which has captured many virulence genes through horizontal transfer during evolution. GadE is an essential transcriptional activator of glutamate decarboxylase (GAD) system, the most efficient acid resistance mechanism in E. coli. The full contribution of GadE to the acid resistance and virulence of pathogenic E. coli O157:H7 remains largely unknown. We inactivated gadE in E. coli O157:H7 Sakai and compared global transcription profiles with that of wild type in exponential and stationary phases of growth using microarrays containing 6088 ORFs from three E. coli genomes. gadE inactivation significantly altered the expression of 60 genes independent of growth phase and 122 genes in a growth phase-dependent manner. Inactivation of gadE markedly down-regulated the expression of gadA, gadB, gadC and many acid fitness island genes in a growth phase-dependent manner. Nineteen genes encoded on the locus of enterocyte effacement (LEE), including ler, showed a significant increase in expression upon gadE inactivation. Altogether, our data indicate that GadE is critical for acid resistance of E. coli O157:H7 and plays an important role in virulence by down-regulating expression of LEE. The results are based on O157:H7 Sakai wild type and gadE mutant exponential and stationary phase cultures grown in MOPS minimal medium. Differences in transcript levels were determined using a mixed model ANOVA in R/MAANOVA which tested for significant differences due to growth phase (exponential or stationary), strain (wild type or mutant) and the interaction of these two factors using the following linear model: array+dye+sample (biological replicate)+ phase+strain+phase*strain. We incorporated the dye-swaps among the biological replicates.
2010-05-18 | E-GEOD-13132 | biostudies-arrayexpress
Project description:Polyamines induce the glutamate decarboxylase acid response system by increasing the level of the σ38 subunit (RpoS) of Escherichia coli RNA polymerase via gadE regulon
| PRJNA278995 | ENA
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 eight samples were analyzed. WT and gadEWX mutant cells were cultured in M9 glucose minimal media at pH 5.5 with biological duplicates.
2015-08-11 | E-GEOD-66481 | biostudies-arrayexpress
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.
2015-08-11 | E-GEOD-66441 | biostudies-arrayexpress
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.
2015-08-11 | GSE66481 | GEO