Escherichia coli K-12
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PROVIDER: PRJNA94513 | ENA |
REPOSITORIES: ENA
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Project description:Gene expression profiles of Escherichia coli K-12 W3110 were compared as a function of steady-state external pH. Cultures were grown with aeration to an optical density at 600 nm of 0.3 in potassium-modified Luria-Bertani medium buffered at pH 5.0, 7.0, and 8.7. For each of the three pH conditions, cDNA from RNA of five independent cultures was hybridized to Affymetrix E. coli arrays. Analysis of variance with a significance level of 0.001 resulted in 98% power to detect genes showing a twofold difference in expression. Normalized expression indices were calculated for each gene and intergenic region (IG). Differential expression among the three pH classes was observed for 763 genes and 353 IGs. Hierarchical clustering yielded six well-defined clusters of pH profiles, designated Acid High (highest expression at pH 5.0), Acid Low (lowest expression at pH 5.0), Base High (highest at pH 8.7), Base Low (lowest at pH 8.7), Neutral High (highest at pH 7.0, lower in acid or base), and Neutral Low (lowest at pH 7.0, higher at both pH extremes). Flagellar and chemotaxis genes were repressed at pH 8.7 (Base Low cluster), where the cell's transmembrane proton potential is diminished by the maintenance of an inverted pH gradient. High pH also repressed the proton pumps cytochrome o (cyo) and NADH dehydrogenases I and II. By contrast, the proton-importing ATP synthase F1Fo and the microaerophilic cytochrome d (cyd), which minimizes proton export, were induced at pH 8.7. These observations are consistent with a model in which high pH represses synthesis of flagella, which expend proton motive force, while stepping up electron transport and ATPase components that keep protons inside the cell. Acid-induced genes, on the other hand, were coinduced by conditions associated with increased metabolic rate, such as oxidative stress. All six pH-dependent clusters included envelope and periplasmic proteins, which directly experience external pH. Overall, this study showed that (i) low pH accelerates acid consumption and proton export, while coinducing oxidative stress and heat shock regulons; (ii) high pH accelerates proton import, while repressing the energy-expensive flagellar and chemotaxis regulons; and (iii) pH differentially regulates a large number of periplasmic and envelope proteins. Keywords: Steady State
2006-03-23 | GSE4511 | GEO
Project description:Gene expression profiles of Escherichia coli K-12 W3110 were compared as a function of steady-state external pH. Cultures were grown with aeration to an optical density at 600 nm of 0.3 in potassium-modified Luria-Bertani medium buffered at pH 5.0, 7.0, and 8.7. For each of the three pH conditions, cDNA from RNA of five independent cultures was hybridized to Affymetrix E. coli arrays. Analysis of variance with a significance level of 0.001 resulted in 98% power to detect genes showing a twofold difference in expression. Normalized expression indices were calculated for each gene and intergenic region (IG). Differential expression among the three pH classes was observed for 763 genes and 353 IGs. Hierarchical clustering yielded six well-defined clusters of pH profiles, designated Acid High (highest expression at pH 5.0), Acid Low (lowest expression at pH 5.0), Base High (highest at pH 8.7), Base Low (lowest at pH 8.7), Neutral High (highest at pH 7.0, lower in acid or base), and Neutral Low (lowest at pH 7.0, higher at both pH extremes). Flagellar and chemotaxis genes were repressed at pH 8.7 (Base Low cluster), where the cell's transmembrane proton potential is diminished by the maintenance of an inverted pH gradient. High pH also repressed the proton pumps cytochrome o (cyo) and NADH dehydrogenases I and II. By contrast, the proton-importing ATP synthase F1Fo and the microaerophilic cytochrome d (cyd), which minimizes proton export, were induced at pH 8.7. These observations are consistent with a model in which high pH represses synthesis of flagella, which expend proton motive force, while stepping up electron transport and ATPase components that keep protons inside the cell. Acid-induced genes, on the other hand, were coinduced by conditions associated with increased metabolic rate, such as oxidative stress. All six pH-dependent clusters included envelope and periplasmic proteins, which directly experience external pH. Overall, this study showed that (i) low pH accelerates acid consumption and proton export, while coinducing oxidative stress and heat shock regulons; (ii) high pH accelerates proton import, while repressing the energy-expensive flagellar and chemotaxis regulons; and (iii) pH differentially regulates a large number of periplasmic and envelope proteins. Experiment Overall Design: Gene expression profiles of Escherichia coli K-12 W3110 were compared as a function of steady-state external pH. Overnight cultures were diluted 1:1000 in potassium-modified Luria-Bertani medium (LBK) buffered with 50 mM HOMOPIPES at pH 5.0, pH 7.0, and pH 8.7. Bacteria were cultured in baffled flasks (less than 10% volume filled) with rotation at 240 rpm, incubated at 37°C to an optical density at 600 nm of 0.3. For each of the three pH conditions, RNA was isolated from five independent cultures. Labeled cDNA was hybridized to Affymetrix antisense arrays according to standard procedures. To analyze the expression levels, Dchip software was used to generate model-based expression indices normalized to sample pH 7 replicate 1. ANOVA was used to identify genes with sitnificant expression differences among the three pH classes (p = 0.001). For genes showing significant differences, the Log2 expression ratios were determined for each pair of pH classes, and significance was determined by Tukey's test (p = 0.001).
2007-09-21 | E-GEOD-4511 | biostudies-arrayexpress
Project description:Substrains in Escherichia coli K-12 MG1655 can possess various swimming motility, which is mostly resulted from different expression levels of flhDC. Here, we studied the swimming motility of two MG1655 substrains, CY562 and CY570. Our results showed that CY562 had no insertion at the promoter region of flhDC and possessed no swimming motility. In contrast, CY570 had an IS-element insertion at the promoter region of flhDC and showed a hyper-motile phenotype. Transcriptomic data suggest that expression of flhDC and the other known flagella genes was much lower in CY562 than that in CY570. Moreover, CY562 possessed higher expression levels for genes involved in stress response, especially acid-stress response, than CY570. Consistently, CY562 showed a higher survival rate under acid stress than CY570. Our data indicate that there are mechanisms conversely regulating motility and stress response in E. coli.
2021-11-15 | GSE165438 | GEO
Project description:In Escherichia coli, pH-dependent gene expression varies with oxygen level. Anaerobic pH-dependent expression ratios were analyzed and compared to the published analysis of aerated cultures (Maurer et al, 2005). E. coli K-12 strain W3110 was cultured in closed tubes containing LBK broth buffered at pH 5.7, pH 7.0, and pH 8.5. Gene expression profiles were obtained by cDNA hybridization to Affymetrix arrays. pH-dependent expression was seen for 1,394 genes, of which 1,002 show no pH dependence under aeration. Four intergenic regions containing regulatory sRNAs were up-regulated by acid anaerobically (ryeA, csrB, gadY, rybC) and one sRNA (ryhA) by acid with aeration. Acid and anaerobiosis co-regulated the gad regulon; drug transporters (mdtEF, mdtL); catabolism of sugar derivatives whose fermentation minimized acid production; and all hydrogenases (hya, hyb, hyc, hyf, hyp). The hydrogenases however were up-regulated at high pH under aeration (observed by real-time PCR). Acid with anaerobiosis down-regulated penicillin-binding proteins (dacACD, mreBC) and ribosome biosynthesis. Ribosome down-regulation may be caused by restriction of anaerobic metabolism at low pH. A core group of 236 genes showed similar pH response with or without aeration. Core genes up-regulated by acid included fimbriae (fimAC), periplasmic chaperones (hdeAB), cyclopropane fatty acid synthase (cfa), the “constitutive” Na+/H+ antiporter (nhaB), and over thirty unidentified proteins. Core genes at high pH included maltodextrin transport (lamB, malEFGKMPQT), ATP synthase, and DNA repair (recA and mutL). Overall, pH and anaerobiosis co-regulated metabolism and transport so as to maximize alternative catabolic options while minimizing acidification or alkalinization of the cytoplasm. Keywords: Steady State
2006-10-01 | GSE4556 | GEO
Project description:The GumB protein is an IgaA-family member that negatively regulates the Rcs stress response system in the bacterium Serratia marcescens. Mutation of the gumB gene results in increased RCs system activity of numerous genes including those involved in flagellar based motility and capsular polysaccharide formation.
2021-06-01 | GSE151031 | GEO
Project description:Bacteria growing as surface-adherent biofilms are better able to withstand chemical and physical stresses than their unattached, planktonic counterparts. Using transcriptional profiling and quantitative PCR, we observed a previously uncharacterized gene, yjfO, to be upregulated during Escherichia coli MG1655 biofilm growth in a chemostat on serine-limited defined medium. A yjfO mutant, developed through targeted insertion mutagenesis, and a yjfO-complemented strain, were obtained for further characterization. While bacterial surface colonization levels (CFU/cm2) were similar in all three strains, the mutant strain exhibited reduced microcolony formation when observed in flow cells, and greatly enhanced flagellar motility on soft (0.3%) agar. Complementation of yjfO restored microcolony formation and flagellar motility to wild type levels. Cell surface hydrophobicity and twitching motility were unaffected by the presence or absence of yjfO. In contrast to the parent strain, biofilms from the mutant strain were less able to resist acid and peroxide stresses. yjfO had no significant effect on E. coli biofilm susceptibility to alkali or heat stress. Planktonic cultures from all three strains showed similar responses to these stresses. Regardless of the presence of yjfO, planktonic E. coli withstood alkali stress better than biofilm populations. Complementation of yjfO restored viability following exposure to peroxide stress, but did not restore acid resistance. Based on its influence on biofilm formation, stress response, and effects on motility, we propose renaming the uncharacterized gene, yjfO, as bsmA (biofilm stress and motility). Transcriptional profiling of duplicate biofilm and planktonic cultures of E. coli MG1655 grown in serine-limited MOPS minimal media.
2010-06-21 | E-GEOD-18362 | biostudies-arrayexpress
Project description:Bacteria growing as surface-adherent biofilms are better able to withstand chemical and physical stresses than their unattached, planktonic counterparts. Using transcriptional profiling and quantitative PCR, we observed a previously uncharacterized gene, yjfO, to be upregulated during Escherichia coli MG1655 biofilm growth in a chemostat on serine-limited defined medium. A yjfO mutant, developed through targeted insertion mutagenesis, and a yjfO-complemented strain, were obtained for further characterization. While bacterial surface colonization levels (CFU/cm2) were similar in all three strains, the mutant strain exhibited reduced microcolony formation when observed in flow cells, and greatly enhanced flagellar motility on soft (0.3%) agar. Complementation of yjfO restored microcolony formation and flagellar motility to wild type levels. Cell surface hydrophobicity and twitching motility were unaffected by the presence or absence of yjfO. In contrast to the parent strain, biofilms from the mutant strain were less able to resist acid and peroxide stresses. yjfO had no significant effect on E. coli biofilm susceptibility to alkali or heat stress. Planktonic cultures from all three strains showed similar responses to these stresses. Regardless of the presence of yjfO, planktonic E. coli withstood alkali stress better than biofilm populations. Complementation of yjfO restored viability following exposure to peroxide stress, but did not restore acid resistance. Based on its influence on biofilm formation, stress response, and effects on motility, we propose renaming the uncharacterized gene, yjfO, as bsmA (biofilm stress and motility).
2009-10-17 | GSE18362 | GEO
Project description:Flagella-driven motility of Salmonella enterica serovar Typhimurium facilitates host colonization. However, the large extracellular flagellum is also a prime target for the immune system. As consequence, expression of flagella is bistable within a population of Salmonella, resulting in flagellated and non-flagellated subpopulations. This allows the bacteria to maximize fitness in hostile environments. The degenerate EAL-domain protein RflP (formerly YdiV) is responsible for the bistable expression of flagella by directing the flagellar master regulatory complex FlhD4C2 to proteolytic degradation. The environmental cues controlling expression of rflP and thus the bistable flagellar biosynthesis remain ambiguous. Here, we demonstrate that RflP responds to cell envelope stress and alterations of outer membrane integrity. Lipopolysaccharide (LPS) truncation mutants of Salmonella Typhimurium exhibited increasing motility defects due to downregulation of flagellar gene expression. Transposon mutagenesis and genetic profiling revealed that σ24 (RpoE) and Rcs phosphorelay-dependent cell envelope stress response systems sense modifications of lipopolysaccharide, low pH activity of the complement system. This subsequently results in activation of RflP expression and degradation of FlhD4C2 via ClpXP. We speculate that diverse hostile environments inside the host might result in cell envelope damage and would thus trigger the repression of resource-costly and immunogenic flagella biosynthesis via activation of the cell envelope stress response.
2018-04-13 | GSE87447 | GEO
Project description:Escherichia coli (E. coli) amine oxidase (ECAO) encoded by tynA gene has been one of the model enzymes to study the mechanism of oxidative deamination of amines to the corresponding aldehydes by amine oxidases. The biological roles of ECAO have been less addressed. Therefore we have constructed a gene deletion Escherichia coli K-12 strain, E. coli tynA-, and used the microarray technique to address its function by comparing the total RNA gene expression to the one of the wt. Our results suggest that tynA is a reserve gene for stringent environmental conditions and its gene product ECAO a growth advantage compared to other bacteria due to H2O2 production.
2015-09-30 | GSE65385 | GEO
Project description:Many neutralophilic bacterial species try to evade acid stress with an escape strategy, which is reflected in the increased expression of genes coding for flagellar components. Extremely acid-tolerant bacteria, such as Escherichia coli, survive the strong acid stress, e.g. in the stomach of vertebrates. Recently, we were able to show that the induction of motility genes in E. coli is strictly dependent on the degree of acid stress, i.e. they are induced under mild acid stress but not under severe acid stress. However, it was not known to what extent fine-tuned expression of motility genes is related to fitness and the ability to survive periods of acid shock. In this study, we demonstrate that the expression of FlhDC, the master regulator of flagellation, is inversely correlated with acid shock survival of E. coli. We encountered this phenomenon when analyzing mutants from the Keio collection in which the expression of flhDC was altered by an IS element. These results suggest a fitness trade-off between acid tolerance and motility.
2024-04-14 | GSE260455 | GEO