Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Escherichia coli K-12, temperature-sensitive mutations in the secA gene have been shown to interfere with protein export. Here we show that the effect of a secA mutation is strongly pleiotropic on membrane biogenesis. Freeze-fracture experiments as well as cryosections of the cells revealed the appearance of intracytoplasmic membranes upon induction of the SecA phenotype. The permeability barrier of the outer membrane to detergents was lost. Two alterations in the outer membrane may be responsible for this effect, namely the reduced amounts of outer membrane proteins, or the reduction of the length of the core oligosaccharide of the lipopolysaccharide, which was observed in phage-sensitivity experiments and by SDS-polyacrylamide gel electrophoresis. Phospholipid analysis of the secA mutant, grown under restrictive conditions, revealed a lower content of the negatively charged phospholipid cardiolipin and of 18:1 fatty acid compared to those of the parental strain grown under identical conditions. These results are in line with the hypothesis that protein export and lipid metabolism are coupled.
 ...
PMID:Membrane biogenesis in Escherichia coli: effects of a secA mutation. 267 87

Blast cell populations from 32 patients with acute non-lymphoblastic leukaemia of various morphological types have been examined for their ability to stimulate allogeneic T lymphocytes from normal donors in one-way mixed leucocyte culture (MLC). At the same time, these leukaemic cell populations were examined for the amounts of major histocompatibility complex Class I and Class II antigens they expressed, and their ability to release interleukin 1 (IL1) in culture both with and without stimulation by lipopolysaccharide. The abilities of the leukaemic cell populations to stimulate in MLC, and to produce IL1, were found to be associated with the expression of morphological characteristics of monocytic differentiation, and correlated significantly. In contrast, no correlation was observed between the extent of Class I or Class II expression and MLC stimulatory ability. Many myeloblast populations of immature phenotype were unable to stimulate allogeneic T cells despite their strong expression of these antigens. This lack of stimulatory ability was not overcome by the addition of exogenous IL1. We therefore conclude that the correlation between the production of IL1 and MLC stimulatory ability does not necessarily imply a cause/effect relationship, and that the interaction between allo-antigen and the T cell receptor together with a supply of lymphokine 'co-stimulator' is not sufficient to activate resting T lymphocytes. The failure of some Class I and II antigen positive leukaemic blasts to stimulate in MLC even in the presence of exogenous IL1 may be due to the lack of other differentiation-associated cell surface molecules necessary for stable cell-cell interaction.
 ...
PMID:Requirements for the stimulation of allogeneic T lymphocytes by acute non-lymphoblastic leukaemia cells. 296 Apr 48

Atomic absorption spectroscopy of isolated native and EDTA-modified (lipopolysaccharide-depleted) outer membrane revealed trace amounts of potassium, manganese, and iron (1.0-7.0 nmol/mg dry weight outer membrane). Sodium, magnesium, and calcium were approximately one order of magnitude more plentiful, but EDTA-modified outer membrane was deficient in calcium. When metal-binding assays were conducted to find the binding capacity of native and EDTA-modified outer membrane, potassium bound poorly compared with sodium. However, there was no difference in the binding of these ions between the OM preparations. In contrast, reduced amounts of magnesium, calcium, manganese, and iron III bound to the EDTA-modified OM. Partitioning of intact cells in a biphasic dextran-polyethyleneglycol system indicated that the reduced lipopolysaccharide content of the EDTA-modified outer membrane increased the hydrophobicity of the cell surface. Exposure of control and EDTA-treated cells to divalent metal salt solutions before phase partitioning also increased cell surface hydrophobicity. Freeze-etching showed that sodium ions had no effect on the membrane fractures observed in control cells, but with EDTA-treated cells, this cation increased the occurrence of small outer membrane fractures (plateaus) which are characteristic of EDTA treatment. Both magnesium and manganese increased the frequency of outer membrane cleavage in control cells, whereas calcium did not. In contrast, all three divalent metallic ions increased the frequency and extent of cleavage in the outer membrane of EDTA-treated cells.
 ...
PMID:Physicochemical roles of soluble metal cations in the outer membrane of Escherichia coli K-12. 309 Dec 29

Amikacin, an aminoglycoside known to inhibit protein synthesis, was found to perturb the outer membrane of a sensitive Pseudomonas aeruginosa strain (ATCC 9027). This perturbation was monitored using electron microscopy and biochemical analyses. Following exposure to 20 micrograms amikacin/mL for 15 min, the outer membrane of exponentially growing cells lost 15% of its protein, 18% of its lipopolysaccharide, and 18% of its phosphate. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that the whole spectrum of outer membrane protein and lipopolysaccharide was affected. Similarly, atomic absorption spectrophotometry revealed that magnesium and calcium were also lost. When cells were treated with amikacin, electron microscopy of negative stains showed a substantial increase in outer membrane blebbing. Freeze fractures revealed changes in membrane fracture pattern and particle distribution, and thin sections revealed a sequential disruption of the cell envelope beginning at the outer membrane and ending at the plasma membrane. This study supports the proposal that aminoglycoside antibiotics cross the outer membrane of Pseudomonas aeruginosa by displacing metal cations necessary to stabilize the organic constituents of the membrane. Their removal results in loss of the outer membrane and the formation of transient small holes which permit the antibiotic access to the cytoplasmic membrane where it is transported into the cytoplasm.
 ...
PMID:Amikacin disrupts the cell envelope of Pseudomonas aeruginosa ATCC 9027. 313 16

Freeze-dried human plasma rich in anti-lipopolysaccharide (anti-LPS) immunoglobulin G was used to treat septic shock (systolic pressure less than or equal to 80 mm Hg, central venous pressure greater than or equal to 6 cm H2O) in obstetric and gynaecological patients. Mortality in conventionally treated patients was 9/19 (47.4%) compared with 1/14 (7.1%) in anti-LPS-treated patients. Anti-LPS caused the mean arterial pressure to rise from 45.1 +/- 7.36 mm Hg to 69.1 +/- 9.07 mm Hg within 75 min of administration. The mean hospital stay of survivors was 28.1 days for controls and 14.2 days for the anti-LPS-treated patients. The development of complications of septic shock was much reduced in the treated group. Anti-LPS thus appears significantly to reduce mortality and morbidity in septicaemia.
 ...
PMID:Anti-lipopolysaccharide immunotherapy in management of septic shock of obstetric and gynaecological origin. 614 65

Eight immunotype lipopolysaccharides (LPSs) of Neisseria meningitidis were prepared by the phenol-water procedure and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and sugar analyses. By SDS-PAGE and a highly sensitive silver strain. N. meningitidis LPSs from cells grown in tryptic soy broth were shown to contain one or two predominant components and a few minor, somewhat higher-molecular-weight components. The molecular sizes of the two predominant components were approximately the same as those of two E. coli rough-type LPSs, one with a complete core and the other with an incomplete core. The molecular weight of the major LPS component varied somewhat among different immunotypes but was estimated to be in the range of 4,200 to 5,000. By sugar analyses, the eight immunotype LPSs were different in their monosaccharide compositions. All contained glucose, galactose, heptose, glucosamine, and 2-keto-3-deoxyoctonate, but in different molar ratios. The growth of N. meningitidis in tryptic soy broth under different levels of aeration resulted in a change in the two major LPS components seen on the SDS-PAGE gel. High aeration increased the amount of the smaller component, whereas low aeration increased the amount of the larger component. Sugar analyses of LPSs from high and low aeration indicated that the larger LPS component contained more galactose residues per molecule. Use of different media for cell growth may also result in small, but noticeable, variations in the LPS components and in the galactose content of the LPS. The observed heterogeneity of N. meningitidis LPS may explain why many strains of N. meningitidis appear to possess more than one immunotype.
 ...
PMID:Heterogeneity and variation among Neisseria meningitidis lipopolysaccharides. 640 79

1. Freeze-fracture electron microscopy and 31P-NMR spectroscopy on native and electrodialyzed lipopolysaccharide from Escherichia coli K12 cells, both above and below the phase transition temperature, are described. 2. Freeze-fracture electron microscopy of native lipopolysaccharide shows ribbon-like structures below (0 and 22 degrees C) and large vesicles above (37 degrees C) the phase transition temperature. Electrodialyzed lipopolysaccharide (sodium salt) occurs in ribbon-like structures at 0, 22 and 37 degrees C if sodium lipopolysaccharide is hydrated in water. If sodium lipopolysaccharide is hydrated in Tris-HCL/NaCl buffer these ribbon-like structures occur only below the phase transition temperature. Above the phase transition temperature stacked sheets are observed. Moreover, in the latter case, the fracture planes contain particles and pits. Upon etching, sodium lipopolysaccharide when hydrated in water appears to form rods and when hydrated in buffer appears to form mainly stacked lamellae both above (37 degrees C) and below (0 degrees C) the phase transition temperature. 3. High resolution 31P-NMR spectra show that the chemical shifts of the phosphorus atoms in native lipopolysaccharide differ from those in electrodialyzed lipopolysaccharide, probably due to conformational and compositional (the disappearance of ions and (poly)electrolytes) changes. The 31P-NMR spectra of native lipopolysaccharide dispersed in Tris-HCL/NaCl buffer are very broad at 20 and at 40 degrees C indicating little motion. At 22 degrees C electrodialyzed lipopolysaccharide also gives a broad spectrum; at 40 degrees C the spectrum is narrower, indicating more motion, and two peaks are visible. After dispersion in H2o and subsequent addition of buffer, the spectrum of electrodialyzed lipopolysaccharide is narrow both at 20 and 40 degrees C, which can be correlated with the rods observed in freeze etching. After treatment with Ca2+, electrodialyzed lipopolysaccharide shows a very broad spectrum at 40 degrees C probably due to immobilization of the lipopolysaccharide. 4. Freeze-fracture electron microscopy and 31P-NMR spectroscopy of liposomes consisting of native lipopolysaccharide and total phospholipids indicate that the phospholipids and the lipopolysaccharide are mainly organized in bilayers. Lipopolysaccharide in such liposomes undergoes more motion than in the absence of phospholipids. Ca2+ does not influence this behaviour.
 ...
PMID:31P nuclear magnetic resonance and freeze-fracture electron microscopy studies on Escherichia coli. II. Lipopolysaccharide and lipopolysaccharide-phospholipid complexes. 699 Sep 86

The polysaccharide part of the lipopolysaccharide isolated from an enteroaggregative Escherichia coli isolated from a young child with diarrhoea in Santiago, Chile (strain 17-2), has been investigated. Sugar and methylation analyses of native and partially degraded polysaccharide together with 1H-NMR and 13C-NMR spectroscopies revealed that the polysaccharide is composed of pentasaccharide repeating units. The structure of the repeating unit of E. coli strain 17-2 O-polysaccharide is: [formula: see text] The structure of the O-polysaccharide from E. coli O3 was shown to be identical to that of E. coli strain 17-2 by sugar and methylation analyses and by 1H-NMR and 13C-NMR spectroscopies.
 ...
PMID:Structural studies of the O-antigenic polysaccharides of Escherichia coli O3 and the enteroaggregative Escherichia coli strain 17-2. 752 Dec 99

The O-antigen polysaccharide of the lipopolysaccharide from the enteroaggregative Escherichia coli O44:H18 has been investigated. Sugar and methylation analysis, 1H- and 13C-NMR spectroscopy revealed that the polysaccharide is composed of pentasaccharide repeating units. The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple bond correlation experiments. The structure of the repeating unit of the O-antigen from Escherichia coli O44:H18 is as follows. [formula: see text]
 ...
PMID:Structural elucidation of the O-antigenic polysaccharide from Escherichia coli O44:H18. 758 90

The polysaccharide part of the lipopolysaccharide obtained from an enteroaggregative Escherichia coli strain isolated from a young child with diarrhoea in Santiago, Chile (strain 73-1) was investigated. Sugar and methylation analyses of native and partially degraded polysaccharide together with 1H-NMR and 13C-NMR spectroscopy revealed that the polysaccharide is built of pentasaccharide repeating units. The structure of the repeating unit of E. coli strain 73-1 O-polysaccharide is (formula: see text)
 ...
PMID:Structural studies of the O-antigenic polysaccharide of an enteroaggregative Escherichia coli strain. 768 49


<< Previous 1 2 3 4 5 6 7 8 Next >>