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

The outer membrane of Pseudomonas aeruginosa PA01 is permeable to saccharides of molecular weights lower than about 6000. Triton X-100/EDTA-soluble outer membrane proteins were fractionated by ion-exchange chromatography in the presence of Triton X-100 and EDTA, and the protein contents of the various fractions analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Each of the major protein bands present in the Triton X-100/EDTA soluble outer membrane was separated from one another. Adjacent fractions were pooled, concentrated and extensively dialyzed to reduce the Triton X-100 concentration. Vesicles were reconstituted from lipopolysaccharide, phospholipids and each of these dialyzed fractions, and examined for their ability to retain [14C]sucrose. Control experiments indicated that the residual levels of Triton X-100 remaining in the dialyzed fractions had no effect on the formation or permeability to saccharides of the reconstituted vesicles. It was concluded that a major outer membrane polypeptide with an apparent weight of 35,000 is a porin, responsible for the size-dependent permeability of the outer membrane.
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PMID:Identification of the protein producing transmembrane diffusion pores in the outer membrane of Pseudomonas aeruginosa PA01. 11 20

Membrane vesicles were prepared from Azotobacter vinelandii spheroplasts by lysis in either potassium phosphate (pH 7.0) or Tris1-acetate (pH 7.8) buffers. These 2 types of preparations differ considerably in their properties: 1) Examination by scanning electron microscopy reveals that the Pi vesicles consist primarily of closed structures 0.6-0.8 micrometer in diameter with a rough or particulate surface similar to that of spheroplasts. The Tris vesicles are significantly smaller, 0.1-0.3 micrometer in diameter, and have a much smoother surface structure. 2) Antisera from rabbits immunized with A. vinelandii lipopolysaccharide antigen will agglutinate Pi vesicles but not Tris vesicles. 3) Tris vesicles have a fourfold higher specific activity of latent H+-ATPase than Pi vesicles. After exposure to Triton X-100 similar ATPase activities are observed for both types of vesicles. 4) Pi vesicles transport calcium in the presence of ATP or lactate at less than 30% of the rats observed for Tris vesicles. 5) Tris vesicles have less than 22% of the transport capacity of Pi vesicles for accumulation of labeled sucrose and less than 3% of the capacity for valinomycin-induced uptake of rubidium observed during respiration. 6) Quinacrine fluorescence intensity is reduced by 30% during lactate oxidation and 20% during ATP hydrolysis by Tris vesicles. Under similar conditions, fluorescence in Pi vesicles is quenched by only 7% and less than 2%, respectively. These findings suggest that Pi vesicles have the normal orientation of the intact cell whereas Tris vesicles have an inverted topology.
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PMID:Isolation of membrane vesicles with inverted topology by osmotic lysis of Azotobacter vinelandii spheroplasts. 14 14

The membrane binding sites for lipopolysaccharide (LPS) were isolated by affinity chromatography of the solubilized membranes prepared from 125I-labeled mouse B-cells and T-cells on an affinity adsorbent prepared by coupling Salmonella minnesota R595 LPS to activated Sepharose 4B. The membrane proteins bound to the affinity adsorbent and eluted with 1.0% Triton X-100 were analyzed according to their mobility on polyacrylamide gel electrophoresis in sodium dodecylsulphate. These membrane proteins were further identified by immunoprecipitation with specific antisera. Immunoglobulins, possibly immunoglobulins M and D, were identified in the eluate from the B-cell membranes. The histocompatibility-2-complex proteins (H-2D, H-2K and Ia antigens) were also found to be binding sites for LPS on both B-cells and T-cells.
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PMID:Binding of bacterial lipopolysaccharide to histocompatibility-2-complex proteins of mouse lymphocytes. 31 42

Isolated membrane fractions of Escherichia coli K-12 yielded complex immunoprecipitate patterns when Triton X-100 and sodium dodecyl sulfate extracts were examined by crossed immunoelectrophoresis with antienvelope immunoglobulins. Twelve of the 46 antigens in the immunoprecipitate patterns of inner (plasma) membranes were identified by zymograms and/or by the use of specific antisera. The following enzyme activities were detected in immunoprecipitates: 6-phosphogluconate dehydrogenase (EC 1.1.1.43); adenosine triphosphatase (EC 3.6.1.3); glutamate dehydrogenase (EC 1.4.1.4), two separate components; malate dehydrogenase (EC 1.1.1.37); dihydroorotate dehydrogenase (EC 1.3.3.1); succinate dehydrogenase (EC 1.3.99.1); lactate dehydrogeanse (EC 1.1.1.27); reduced nicotinamide adenine dinucleotide dehydrogenase (EC 1.6.99.3); protease (EC 3.4.21.1); and glycerol 3-phosphate dehydrogenase (EC 1.1.99.5). The corresponding immunoprecipitate pattern for isolated outer membranes consisted of at least 25 discrete antigens and differed strikingly from that obtained with inner membranes. Two major immunogens were identified as lipopolysaccharide and Braun lipoprotein. A protease-active immunoprecipitate was also detected in this fraction, but attempts to identify the Rosenbusch matrix protein in the crossed immunoelectrophoretic profile were unsuccessful.
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PMID:Immunochemical analysis of inner and outer membranes of Escherichia coli by crossed immunoelectrophoresis. 33 83

Protein vaccines were prepared from the serotype antigen of group B Neisseria meningitidis strain M986. The detergents Triton X-100, Emulphogene BC-720, and deoxycholate were used to removed the toxic lipopolysaccharide (LPS) portion of the serotype antigen. The LPS was most preferentially solubilized by Emulphogene. Guinea pigs were immunized with one or two doses of vaccine given intramuscularly without adjuvants and the antibody response quantitated by an enzyme-linked immunosorbant assay. Immunization with graded doses of vaccine between 25 to 200 microgram protein indicated a wide range of effective dosage and that a two-dose immunization schedule was superior to a single immunization. The vaccines elicited peak mean serum antibody levels of approximately 30 microgram/ml with bactericidal titers of 1:1,600-1:6,400. The peak antibody levels occurred 5-6 wk after immunization and persisted above preimmune levels for several months. To evaluate the protective effects of immunization, stainless steel springs were implanted subcutaneously into the guinea pigs. The resulting chambers, in unimmunized animals, could be infected with less than 100 type 2 organisms. A single 25-50 microgram dose of vaccine protected 50% of animals from challenge by 5 X 10(5) type 2 meningococci, and as little as 1 microgram vaccine significantly reduced the severity of infection. A two-dose immunization schedule was best and provided nearly complete protection for at least 4 mo against type 2 strains of meningococcal groups B, C, and Y.
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PMID:Protection against group B meningococcal disease. III. Immunogenicity of serotype 2 vaccines and specificity of protection in a guinea pig model. 41 64

The antiphagocytic antigen (antigen [a]) comprising the microcapsule of a strain of Campylobacter fetus subsp. intestinalis has been purified from culture supernatants by ammonium sulfate fractionation and free-flow electrophoresis. Antigen [a] is a glycoprotein containing about 4% carbohydrate consisting of hexose, pentose, and methylpentose. The composition of the protein was typical of bacterial extramural structural proteins in its low content of basic, aromatic, and sulfur-containing amino acids. The protein had a high content of aspartic acid, threonine, glycine, and alanine. Antigen [a] had an Rf of 0.33 on polyacrylamide gel electrophoresis and a molecular weight calculated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis of approximately 98,000. In contrast to its free form in culture supernatants, antigen [a] in vesicles derived from sheared cells appeared to exist in a complex with lipopolysaccharide. This complex could be dissociated by ethylenediaminetetraacetic acid or by ethylenediaminetetraacetic acid plus Triton X-100. A mutant strain that lacked a microcapsule, when incubated with soluble antigen [a] in a calcium medium, became agglutinable by monospecific [a] antiserum and showed an additional structural layer similar in appearance to the microcapsule on its cell wall. Points of similarity are emphasized between antigen [a] of C. fetus and the outer structural protein of the taxonomically related Spirillum serpens.
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PMID:Microcapsule of Campylobacter fetus: chemical and physical characterization. 73 Mar 87

Mutants of Escherichia coli have been analyzed which miss two of the major proteins of the outer cell envelope membrane. The two proteins I and II, normally are present at high concentrations (about 10(5) copies per cell). In such mutants, as compared with wild type, the phospholipid-to-protein ratio in the outer membrane has increased by a factor of 2.3 causing a considerable difference in density between wild type and mutant membranes. The concentrations of two other major components of the outer membrane, lipopolysaccharide and Braun's lipoprotein, did not change. The protein-deficient mutants do not exhibit gross functional defects in vitro. An increased sensitivity to EDTA and a slight such increase to dodecyl sulfate (but not to deoxycholate or Triton X-100) was observed, loss of so-called periplasmic enzymes was not found, and other differences to wild type are marginal. The mutants can grow with normal morphology. It is not possible, however, to prepare "ghosts" (particles of size and shape of the cell without murein, surrounded by a derivative of the outer membrane, and possessing the major proteins of this membrane) from them. This fact confirms our earlier suggestion that the proteins in question are required for the shape maintenance phenomenon in ghosts, and the mutants reject the speculation that these proteins are involved in the expression of the genetic information specifying cellular shape. Freeze-fracturing showed that in mutant cells, and in sharp contrast to wild type, the far predominant fracture plane is within the outer membrane. The concentration of the well known densely packed particles at the outer, concave leaflet of this fracture plane is greatly reduced. It was not possible, however, to clearly establish that one or the other protein is part of these particles because these ultrastructural differences were not apparent in mutants missing either one of the proteins only. The biochemical and ultrastructural data allow the conclusion that the loss of two major proteins and the concomitant increase of phospholipid concentration has changed the architecture of the outer membrane from a highly oriented structure, with a large fraction of protein-protein interaction, to one predominantly exhibiting planar lipid bilayer characteristics. E. coli thus can assemble rather different outer membranes, a fact excluding that outer membrane formation constitutes a highly ordered or strictly sequential assembly-line process.
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PMID:Mutational change of membrane architecture. Mutants of Escherichia coli K12 missing major proteins of the outer cell envelope membrane. 78 90

Lipopolysaccharides have been extracted from Escherichia coli O111:B4 by phenol extraction and by a new method employing aqueous butanol. Both methods yield very similar lipopolysaccharide preparations. Gel filtration chromatography of either preparation yields two physically and chemically distinct lipopolysaccharide fractions. One fraction contains lipopolysaccharide molecules with long antigenic side chains. It acts like a highly asymmetric unit with an apparent weight of 1.5 times 10-6 and is not dissociated by detergents or deacylation. The second fraction has a short antigenic side chain and can be dissociated by sodium dodecyl sulfate and Triton X-100 into units of approximately 90,000. Some properties of the lipopolysaccharide fractions vary with the method of extraction.
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PMID:Fractions of lipopolysaccharide from Escherichia coli O111:B4 prepared by two extraction procedures. 80 83

Borrelia burgdorferi resembles gram-negative bacteria in having both cellular and outer membranes. We previously showed that a lipopolysaccharide (LPS)-like material could be extracted from B. burgdorferi with phenol-chloroform-petroleum ether (PCP). The PCP extract of B. burgdorferi exhibited biological activity in several in vitro assays (e.g., mitogenicity, pyrogenicity, and cytokine release). These activities suggested the presence of endotoxin. The PCP extract of B. burgdorferi, however, also contained a small amount of protein. Preliminary studies showed that monoclonal antibody prepared against this protein inhibited the mitogenic activity of the PCP extract toward murine spleen cells. The current study was therefore undertaken to characterize this protein and to establish methods for its separation from the LPS. The PCP-extracted protein consisted of a single, low-molecular-weight lipoprotein (apparent M(r), 10,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) (SDS-PAGE). By protein analysis, it accounted for 2% of the dry weight of defatted cells, thus making it a major constituent of the spirochete. It was purified from the LPS by initial extraction into 10% Triton X-100 followed by immunoaffinity chromatography in the presence of detergent. On removal of the LPS, the purified lipoprotein formed aggregates stable to SDS-PAGE which were detectable on Western blots (immunoblots) probed with either the monoclonal antibody or polyclonal antiserum. From a plot of the aggregate molecular weight versus aggregate size, a monomer molecular weight of 7,500 was obtained. Indirect immunofluorescence with the monoclonal antibody showed that the lipoprotein was exposed at the surface of the spirochete in only a small percentage of cells. The lipoprotein was present in several strains of B. burgdorferi but absent in other Borrelia spp., treponemes, and gram-negative human pathogens, indicating species specificity.
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PMID:Purification and immunological characterization of a major low-molecular-weight lipoprotein from Borrelia burgdorferi. 145 30

Infections by Trypanosoma lewisi are characterized by hyporesponsiveness of the immune system during the early phase of parasitaemia. Blastogenic response of normal rat spleen cells to amphiphilic and hydrophilic components of Triton X-114 solubilized epimastigote forms of T. lewisi which characterizes the early phase of infection showed that suppression of responses to mitogens Concanavalin A (Con-A) and lipopolysaccharide (LPS) occurred exclusively with the amphiphilic fraction that consists of integral surface membrane constituents. The Con-A-induced suppression by the amphiphilic constituents was ablated by addition of exogenous IL-2 or by the removal of the adherent cell population in the cultures. This suggests that the integral surface membrane components play an important regulatory role in infections with Trypanosoma lewisi, through complex mechanisms that probably involve the B cells and suppressor macrophages; the suppressor macrophages probably produce a suppressor factor that inhibits the proliferation of T helper cells and subsequently the production of interleukin-2.
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PMID:Cellular responses to phase fractions of Trypanosoma lewisi. 155 27


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