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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydrolysis of the chromogenic beta-lactam nitrocefin by periplasmic beta-lactamase in intact Pseudomonas aeruginosa cells was used to assess the influence of various compounds on the permeability of the P. aeruginosa outer membrane. In addition to the five previously described outer membrane-active compounds EDTA, polymyxin B, gentamicin, poly-L-lysine, and Tris, seven other compounds were shown to increase outer membrane permeability to nitrocefin by 14- to 63-fold. These other compounds included poly-L-ornithine, neomycin, cetyltrimethylammonium bromide, nitrilotriacetate, L-ascorbate, and acetylsalicylate. In each case, Mg2+ ions antagonized, to different extents, the enhancement of outer membrane permeability. The same compounds increased the permeability of the outer membrane to the protein lysozyme and to the hydrophobic fluorescent probe 1-N-phenylnaphthylamine, although L-ascorbate and acetylsalicylate showed only very weak enhancement of uptake in these assays. In this report, we discuss the possibility that these compounds act at a common outer membrane site at which divalent cations noncovalently cross-bridge adjacent lipopolysaccharide molecules.
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PMID:Compounds which increase the permeability of the Pseudomonas aeruginosa outer membrane. 643 88

Properties of Ca2+- or Ba2+-dependent transfection and transformation in Escherichia coli were examined, using phi X174 replicative-form (RF) DNA and plasmid DNA. For the transfection and transformation, a heat pulse step was dispensable and the yield of transfectants was, in most E. coli strains, rather reduced by the heat treatment. The heat pulse step was also detrimental for the transformation of certain strains such as lipopolysaccharide mutants, The first stage of the DNA uptake process (formation of DNA . recipient cell complex) was dependent on low temperature and Ca2+ ion. A substantial amount of the complexed RF-DNA was released from the bacteria, by washing with a chilled Tris buffer. Although a RF-DNA . cell complex was formed even at 37 degree C or in chilled 0.05 m MgC12, the complex did not yield transfectants.
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PMID:Sensitivity of Escherichia coli to viral nucleic acid. XVI. Temperature conditions for Ca2+-dependent dna uptake in Escherichia coli. 646 Nov 41

Antisera against isolated outer membrane (OM) proteins I and II of Escherichia coli O26 K60 were elicited in rabbits. Antisera obtained after intramuscular administration with Freund's complete adjuvant showed high titres of specific antibodies. Intravenous administration of the same preparations yielded a considerable antibody response against bacterial lipopolysaccharide, a minor contaminant of the protein preparations. Antibody titres against OM proteins I and II, lipopolysaccharide and murein-lipoprotein were determined by the enzyme-linked immunosorbent assay (ELISA) in these sera, and in antisera elicited against whole formaldehyde-fixed bacteria or isolated OM. Comparison of ELISA with single radial immunodiffusion and interfacial immunoprecipitation tests revealed that ELISA was not only the most uniformly applicable, but also the most specific and the most convenient method. In double diffusion tests no cross-reactivity between proteins I and II was seen. Antibodies against proteins I and II, lipopolysaccharide and lipoprotein could be specifically absorbed from the sera with the appropriate antigen preparations. Absorption experiments with intact E. coli O26 K60, Tris/EDTA-sheared bacteria and isolated OM revealed that antibodies against protein I were hardly absorbed at all probably because the antibody, evoked against denatured protein I, did not react with the protein in its native configuration. Antibodies against protein II and lipoprotein were absorbed by intact as well as by sheared bacteria, but to a much greater extent by isolated OM, which indicates that these OM components are accessible from the outside, but that they are situated relatively deep in the OM structure.
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PMID:Preparation and quantitative determination of antibodies against major outer mambranes proteins of Escherichia coli O26 K60. 677 43

Polymyxin-resistant pmrA mutants of Salmonella typhimurium differed from their parents in that they were resistant to tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-lysozyme, tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-deoxycholate, and tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-bacitracin. Tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate released about 50% less lipopolysaccharide from the pmrA strains than from the parental strains when the bacteria were grown in L-broth containing 2 mM Ca2+. Protamine, polylysine, octapeptin, benzalkonium chloride, cold NaCl, cold MgCl2, or cold tris(hydroxymethyl)aminomethane hydrochloride (pH 7.2) caused no leakage or markedly less leakage of periplasmic beta-lactamase from a pmrA mutant than from its parent strain. pmrA mutants were more resistant than their parent strains to protamine and polylysine but not to octapeptin or benzalkonium chloride, as measured by the ability of these agents to kill the bacteria or to sensitize them to deoxycholate-induced lysis. The pmrA strains did not differ from their parent strains in sensitivity to several antibiotics, in porin function (as measured by cephaloridine diffusion across the outer membrane), or in outer membrane-associated phospholipase A activity.
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PMID:Increased outer membrane resistance to ethylenediaminetetraacetate and cations in novel lipid A mutants. 679 77

Seventy-two field strains of smooth Salmonella cholerae-suis var kunzendorf were obtained from outbreaks of swine parathyroid. The field strains were examined for susceptibility to killing by antibody-complement (Ab-C) after they were exposed to Tris-EDTA, lysozyme, or saline solution. Considerable differences were found in susceptibility to killing by Ab-C in the strain population. Some strains were highly sensitive to Ab-C under all experimental conditions, whereas others became sensitive only after prior exposure to Tris-EDTA or to lysozyme. One strain was resistant to all treatments. Numerical decrease of colony-forming units by Tris-EDTA affected the population independently of decrease of the colony-forming units by Ab-C in saline solution. Evidence was obtained to indicate that Tris-EDTA may inhibit growth of S cholerae-suis in addition to the documented effect of Tris-EDTA on the release of lipopolysaccharide from the cell wall of gram-negative bacteria.
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PMID:Sensitivity of smooth Salmonella cholerae-suis var kunzendorf field strains to antibody complement under various conditions. 680 77

Cell envelopes prepared from smooth and rough strains of Brucella were characterized on the basis of lipopolysaccharide and protein content. The action of three kinds of detergents on Brucella cell envelopes and Escherichia coli control cell envelopes was examined on the basis of the proteins and lipopolysaccharides that were extracted. As compared with those of E. coli, Brucella cell envelopes were resistant to nonionic detergents. Zwittergents 312 and 316 were most effective in extracting E. coli cell envelopes, and Zwittergent 316 was most effective in extracting Brucella cell envelopes. Sarkosyl extracted proteins but extracted only trace amounts of lipopolysaccharides from cell envelopes of both bacteria. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the Sarkosyl-resistant proteins revealed a composition similar to that of the proteins exposed on the surfaces of viable cells, as determined by the lactoperoxidase-125I radioiodination method. EDTA, with either Tris-HCl or Tris-HCl-Triton X-100, did not have detectable effects on Brucella cell envelopes. Ultracentrifugation of purified lipopolysaccharides in detergents and EDTA demonstrate that, in contrast to that of E. coli, Brucella lipopolysaccharide was not stabilized by divalent cations. Sarkosyl was ineffective in dispersing lipopolysaccharides, whereas the action of Zwittergents was related to the length of their alkyl chains.
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PMID:Effects of nonionic, ionic, and dipolar ionic detergents and EDTA on the Brucella cell envelope. 681 15

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.
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PMID:31P nuclear magnetic resonance and freeze-fracture electron microscopy studies on Escherichia coli. II. Lipopolysaccharide and lipopolysaccharide-phospholipid complexes. 699 Sep 86

The effect of tris(hydroxymethyl)aminomethane (Tris) buffer on outer membrane permeability was examined in a smooth strain (D280) and in a heptose-deficient lipopolysaccharide strain (F515) of Escherichia coli O8. Tris buffer (pH 8.00) was found to increase outer membrane permeability on the basis of an increased Vo of whole-cell alkaline phosphatase activity and on the basis of sensitivity to lysozyme and altered localization pattern of alkaline phosphatase. The Tris buffer-mediated increase in outer membrane permeability was found to be dependent upon the extent of exposure to and concentration of the Tris buffer. The Tris buffer effects were demonstrated not to be due to allosteric activation of cell-associated alkaline phosphatase and were specific for Tris buffer. Exposure of cells to Tris resulted in the release of a limited amount of cell envelope component. Investigators utilizing Tris buffer are cautioned that Tris is not physiologically inert and that it may interact with the system under investigation.
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PMID:Tris(hydroxymethyl)aminomethane buffer modification of Escherichia coli outer membrane permeability. 700 85

Thermal damage to the outer membrane of Escherichia coli W3110 was studied. When E. coli cells were heated at 55 degrees C in 50 mM Tris-hydrochloride buffer at pH 8.0, surface blebs were formed on the cell envelope, mainly at the septa of dividing cells. Membrane lipids were released from the cells during the heating period, and part of the released lipids formed vesicle-like structures from the membrane. This vesicle fraction had a lipopolysaccharide to phospholipid ratio similar to that of the outer membrane of intact cells, whereas it had a lower content of protein than the isolated outer membrane. After heating bacterial cells at 55 degrees C for 30 min, the resulting leakage from the cells of a periplasmic enzyme, alkaline phosphatase, amounted to 52% of the total activity, whereas no release of a cytoplasmic enzyme, glucose-6-phosphate dehydrogenase, was detected. The results obtained suggest that surface blebs formed by heat treatment almost completely consist of the outer membrane and that the blebs may be gradually released from the cell surface into the heating menstruum to partially form vesicles.
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PMID:Heat-induced blebbing and vesiculation of the outer membrane of Escherichia coli. 705 91

The optimal conditions for the detection of outer membrane proteins (OMPs) and lipopolysaccharide (LPS) of Pasteurella haemolytica by immunoblotting were evaluated. The variables examined included the equilibration time of the gels before transfer, composition of the transfer buffer, type of blotting membrane, blocking agent, effect of the zwitterionic detergent Empigen BB on protein renaturation, and the development reagent. The composition of the transfer buffer and time of gel equilibration significantly affected the efficiency of transfer of both OMPs and LPS. However, the optimal conditions for the transfer of OMPs were not the same as those for LPS. Thus, optimal transfer of OMPs occurred in Tris-glycine buffer, with prior equilibration of the gels to allow for expansion, whereas optimal transfer of LPS was achieved in Tris-glycine-methanol buffer with no equilibration of the gels. In Tris-glycine-methanol buffer, gel equilibration resulted in a significantly reduced transfer of both OMPs and LPS, probably due to the removal of SDS from these components. The use of Zeta-Probe blotting membrane which, unlike nitrocellulose, does not require methanol for optimal protein binding, did not result in improved binding of OMPs or LPS in the absence of methanol and, even after prolonged blocking (> 2 h), gave higher background staining than did nitrocellulose. Effective blocking of nitrocellulose was achieved with 3% (w/v) gelatin, 2.5% (w/v) skimmed milk or 0.3% (v/v) Tween 20, whereas increased background staining occurred with 1% (w/v) bovine serum albumin or 1% (w/v) ovalbumin. The incorporation of Empigen BB in the primary antibody buffer did not improve antibody recognition of proteins as a result of their renaturation. For the horseradish-peroxidase enzyme development system, the substrate 3,3'-diaminobenzidine tetrahydrochloride was more sensitive, and developed more quickly, than 4-chloro-1-naphthol, but faded more rapidly after drying of the membrane. 4-chloro-1-naphthol was more suitable for identifying OMPs because less background staining occurred, whereas 3,3'-diaminobenzidine tetrahydrochloride was more suitable for the detection of LPS due to its greater sensitivity.
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PMID:Evaluation of different methods for the detection of outer membrane proteins and lipopolysaccharides of Pasteurella haemolytica by immunoblotting. 750 80


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