An extracellular glycolipid produced by Escherichia coli grown under lysine-limiting conditions.
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ABSTRACT:
SUBMITTER: Bishop DG
PROVIDER: S-EPMC1207076 | biostudies-other | 1965 Aug
REPOSITORIES: biostudies-other
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Project description:Lysine limitation during growth of the lysine-requiring mutant of Escherichia coli 12408 resulted in the excretion of a complex containing 60% of lipopolysaccharide, 26% of extractable phospholipid and 11% of protein. The complex was obtained from the culture filtrate in yields of about 0.5g./l. by precipitation with chloroform or gel filtration; some purification steps are described. The greater part of the phospholipid consisted of phosphatidylethanolamine, which contained four main fatty acids; two monoenoic acids and a cyclopropane acid were esterified mainly in the beta-position, and a saturated acid was located mainly in the gamma-position. The protein component was relatively insoluble and contained an excess of acidic over basic amino acids and little cystine. The lipopolysaccharide resembled in composition the intracellular lipopolysaccharides from rough strains of E. coli. Both protein and lipopolysaccharide constituents of the complex were serologically active; the complex was less toxic than the purified lipopolysaccharide. In the electron microscope the complex showed a mixture of particles of various sizes and shapes. Rods and hollow spheroids (diameter 12-200mmu) were most common and resembled the particles previously found surrounding cells actively excreting the complex. The chloroform-precipitated material showed a tubular lamellar structure. Soluble lipopolysaccharide prepared from the complex also consisted of hollow spheres and rods.
| S-EPMC1270384 | biostudies-other
Project description:Lipopolysaccharide was prepared from the extracellular lipoglycopeptide produced by the lysine-requiring mutant Escherichia coli A.T.C.C. 12408 grown under lysine-limiting conditions. The lipid moiety, containing glucosamine phosphate and four fatty acids (lauric acid, myristic acid, beta-hydroxymyristic acid and palmitic acid) corresponded in composition to lipid A of known bacterial lipopolysaccharides. The components of the polysaccharide moiety were d-glucose, d-galactose, l-glycero-d-manno-heptose, 3-deoxy-2-oxo-octonic acid, ethanolamine and phosphate. These are the constituents of the polysaccharide of the cell-wall antigens from rough strains of E. coli. Lipopolysaccharides were also prepared from whole cells of E. coli 12408 grown with excess or limited amounts of lysine; they were identical in carbohydrate composition with the extracellular lipopolysaccharide. The biological properties of this material also resembled those of known lipopolysaccharides; it was antigenic, pyrogenic, toxic and had adjuvant activity.
| S-EPMC1264956 | biostudies-other
Project description:Escherichia coli strain MG1655 was grown in a New Brunswick Scientific Bioflow III Biofermentor under continuous culture (chemostat) conditions. Cells were grown in defined media containing 54 mM glycerol as the sole and limiting source of energy and carbon. The working volume was 1 litre, and the dilution rate 0.2 h-1. In order to establish anaerobic growth, nitrogen was sparged through the chemostat medium prior to inoculation and throughout the course of the experiment at a rate of 0.2 l/min. No dissolved oxygen was detectable using the OxyProbe. Sodium fumarate was added to anaerobic medium at a final concentration of 50 mM to act as a terminal electron acceptor. Cells were grown as above to steady-state, At steady-state, GSNO was added to the chemostat culture and to the nutrient feed at a final concentration of 200 uM unless otherwise stated. Samples were taken immediately prior to the addition of GSNO and after a period of 5 min exposure to GSNO for subsequent analysis using microarrays. Cells were harvested directly into RNA Protect (Qiagen) to stabilize RNA, and total RNA was purified using Qiagen’s RNeasy Mini kit as recommended by the suppliers. Equal quantities of RNA from control and GSNO-supplemented cultures were labelled using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes. The average signal intensity and local background correction were obtained using a commercially available software package from Biodiscovery, Inc (Imagene, version 4.0 and GeneSight, version 3.5). The mean values from each channel were log2 transformed and normalised using the Lowess method to remove intensity-dependent effects in the log2(ratios) values. The Cy3/Cy5 fluorescent ratios were calculated from the normalized values. Keywords: dose response
2005-04-06 | GSE2129 | GEO
Project description:Bacterial motility is thought to play an important role in virulence. We have previously shown that proficient bacterial swimming and swarming in vitro is correlated with the persistent intramammary infection phenotype observed in cattle. However, little is known about the gene regulation differences important for different motility phenotypes in Escherichia coli. In this work, three E. coli strains that cause persistent bovine mastitis infections were grown in three media that promote different types of motility (planktonic, swimming, and swarming). Using whole-transcriptome RNA sequencing, we identified a total of 935 genes (~21% of the total genome) that were differentially expressed in comparisons of the various motility-promoting conditions. We found that approximately 7% of the differentially expressed genes were associated with iron regulation. We show that motility assays using iron or iron chelators confirmed the importance of iron regulation to the observed motility phenotypes. Because of the observation that E. coli strains that cause persistent infections are more motile, we contend that better understanding of the genes that are differentially expressed due to the type of motility will yield important information about how bacteria can become established within a host. Elucidating the mechanisms that regulate bacterial motility may provide new approaches in the development of intervention strategies as well as facilitate the discovery of novel diagnostics and therapeutics. IMPORTANCE Bacteria can exhibit various types of motility. It is known that different types of motilities can be associated with virulence. In this work, we compare gene expression levels in bacteria that were grown under conditions that promoted three different types of E. coli motility. Better understanding of the mechanisms of how bacteria can cause an infection is an important first step to better diagnostics and therapeutics.
| S-EPMC5072449 | biostudies-literature
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.
2013-11-04 | GSE49296 | GEO
Project description:Bile salts exhibit potent antibacterial properties, acting as detergents to disrupt cell membranes and as DNA-damaging agents. Although bacteria inhabiting the intestinal tract are able to resist bile's antimicrobial effects, relatively little is known about how bile influences virulence of enteric pathogens. Escherichia coli O157:H7 is an important pathogen of humans, capable of causing severe diarrhea and more serious sequelae. In this study, the transcriptome response of E. coli O157:H7 to bile was determined. Bile exposure induced significant changes in mRNA levels of genes related to virulence potential, including a reduction of mRNA for the 41 genes making up the locus of enterocyte effacement (LEE) pathogenicity island. Bile treatment had an unusual effect on mRNA levels for the entire flagella-chemotaxis regulon, resulting in two- to four-fold increases in mRNA levels for genes associated with the flagella hook-basal body structure, but a two-fold decrease for "late" flagella genes associated with the flagella filament, stator motor, and chemotaxis. Bile salts also caused increased mRNA levels for seventeen genes associated with iron scavenging and metabolism, and counteracted the inhibitory effect of the iron chelating agent 2,2'-dipyridyl on growth of E. coli O157:H7. These findings suggest that E. coli O157:H7 may use bile as an environmental signal to adapt to changing conditions associated with the small intestine, including adaptation to an iron-scarce environment.
| S-EPMC3769235 | biostudies-literature
Project description:BackgroundPost-translational modification (PTM) of proteins is central to many cellular processes across all domains of life, but despite decades of study and a wealth of genomic and proteomic data the biological function of many PTMs remains unknown. This is especially true for prokaryotic PTM systems, many of which have only recently been recognized and studied in depth. It is increasingly apparent that a deep sampling of abundance across a wide range of environmental stresses, growth conditions, and PTM types, rather than simply cataloging targets for a handful of modifications, is critical to understanding the complex pathways that govern PTM deposition and downstream effects.ResultsWe utilized a deeply-sampled dataset of MS/MS proteomic analysis covering 9 timepoints spanning the Escherichia coli growth cycle and an unbiased PTM search strategy to construct a temporal map of abundance for all PTMs within a 400 Da window of mass shifts. Using this map, we are able to identify novel targets and temporal patterns for N-terminal N α acetylation, C-terminal glutamylation, and asparagine deamidation. Furthermore, we identify a possible relationship between N-terminal N α acetylation and regulation of protein degradation in stationary phase, pointing to a previously unrecognized biological function for this poorly-understood PTM.ConclusionsUnbiased detection of PTM in MS/MS proteomics data facilitates the discovery of novel modification types and previously unobserved dynamic changes in modification across growth timepoints.
| S-EPMC5392934 | biostudies-literature
Project description:Escherichia coli strain MG1655 was grown in a New Brunswick Scientific Bioflow III Biofermentor under continuous culture (chemostat) conditions. Cells were grown in defined media containing 54 mM glycerol as the sole and limiting source of energy and carbon. The working volume was 1 litre, and the dilution rate 0.2 h-1. In order to establish anaerobic growth, nitrogen was sparged through the chemostat medium prior to inoculation and throughout the course of the experiment at a rate of 0.2 l/min. No dissolved oxygen was detectable using the OxyProbe. Sodium fumarate was added to anaerobic medium at a final concentration of 50 mM to act as a terminal electron acceptor. Cells were grown as above to steady-state, At steady-state, GSNO was added to the chemostat culture and to the nutrient feed at a final concentration of 200 uM unless otherwise stated. Samples were taken immediately prior to the addition of GSNO and after a period of 5 min exposure to GSNO for subsequent analysis using microarrays. Cells were harvested directly into RNA Protect (Qiagen) to stabilize RNA, and total RNA was purified using Qiagenâs RNeasy Mini kit as recommended by the suppliers. Equal quantities of RNA from control and GSNO-supplemented cultures were labelled using nucleotide analogues of dCTP containing either Cy3 or Cy5 fluorescent dyes. The average signal intensity and local background correction were obtained using a commercially available software package from Biodiscovery, Inc (Imagene, version 4.0 and GeneSight, version 3.5). The mean values from each channel were log2 transformed and normalised using the Lowess method to remove intensity-dependent effects in the log2(ratios) values. The Cy3/Cy5 fluorescent ratios were calculated from the normalized values.
2010-06-10 | E-GEOD-2129 | biostudies-arrayexpress
Project description:Lysine acetylation is thought to provide a mechanism for regulating metabolism in diverse bacteria. Indeed, many studies have shown that the majority of enzymes involved in central metabolism are acetylated and that acetylation can alter enzyme activity. However, the details regarding this regulatory mechanism are still unclear, specifically with regard to the signals that induce lysine acetylation. To better understand this global regulatory mechanism, we profiled changes in lysine acetylation during growth of Escherichia coli on the hexose glucose or the pentose xylose at both high and low sugar concentrations using label-free mass spectrometry. The goal was to see whether lysine acetylation differed during growth on these two different sugars. No significant differences, however, were observed. Rather, the initial sugar concentration was the principal factor governing changes in lysine acetylation, with higher sugar concentrations causing more acetylation. These results suggest that acetylation does not target specific metabolic pathways but rather simply targets accessible lysines, which may or may not alter enzyme activity. They further suggest that lysine acetylation principally results from conditions that favor accumulation of acetyl phosphate, the principal acetate donor in E. coliIMPORTANCE Bacteria alter their metabolism in response to nutrient availability, growth conditions, and environmental stresses using a number of different mechanisms. One is lysine acetylation, a posttranslational modification known to target many metabolic enzymes. However, little is known about this regulatory mode. We investigated the factors inducing changes in lysine acetylation by comparing growth on glucose and xylose. We found that the specific sugar used for growth did not alter the pattern of acetylation; rather, the amount of sugar did, with more sugar causing more acetylation. These results imply that lysine acetylation is a global regulatory mechanism that is responsive not to the specific carbon source per se but rather to the accumulation of downstream metabolites.
| S-EPMC6456854 | biostudies-literature
Project description:A total of 4388/4385 genes' transcripts (under aerobic/microaerobic condition, respectively) were identified. Among them, 105 and 71 transcripts were confidently determined to be up- or down-regulated by more than 4 folds with false discovery rate (FDR) p value more than 1, respectively. Additionally, 49 known regulatory non-coding small RNAs (sRNAs) were detected, and 18 sRNAs were differentially abundant (more than 1.5 fold-change). Functional characterizations were revealed that the major differential expression genes were involved in (i) acid response/cation homeostasis (ex: gadAXW, and hdeAB-yhiD operons), (ii) cell adhesion/biofilm formation (ex; fimAICDFGH, and csgDEFG operons), (iii) electron transportation (ex: cydAB, and nrdHIEF operons), (iv) ion transporter (ex: efeU, and efeOB operons), (v) Iron-sulfur cluster assembly (ex: iscRSUA and sufABCDSE operons), and (vi) the undoubtable anaerobic respiration/fermentation (ex: hyaABCDEF and hybOABCDEFG operons) & aerobic respiration (ex: sdhDAB and sucABCDSE operons).
2022-03-15 | GSE189154 | GEO