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

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

The cell envelope of Neisseria gonorrhoeae, colony type 4, was studied. Outer membrane was isolated by lysozyme and ethylenediaminetetraacetic acid treatment of plasmolyzed cells according to Wolf-Watz et al. (1973). The degree of purity of the membrane preparations was checked by electron microscopy. The membrane fraction obtained had a density of 1.25 g/cm(3), was rich in phospholipase A and lysophospholipase, and contained only 10% of the total membrane activity of succinate dehydrogenase and d-lactate dehydrogenase. The outer membrane protein profile after sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed at least six major proteins. The predominating protein showed a molecular weight of 35,000. The lipopolysaccharide component was characterized by gas chromatography. The carbohydrates found were galactose, glucose, and glucosamine. d-Glycero-l-manno-heptose was present in very low amounts. Lipid A contained lauric acid, stearic acid, and beta-hydroxy-myristic acid. About 20% of the fatty acids in the outer membrane was derived from lipid A. The phospholipids were characterized as phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. There was no evidence for a lipoprotein anchored to the peptidoglycan. The peptidoglycan of N. gonorrhoeae was of the chemotype I. The cell envelope of N. gonorrhoeae was found to be highly permeable to gentian violet. Cell envelopes of one penicillin-resistant and two penicillin-sensitive strains were compared. Only moderate differences in fatty acid composition were found.
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PMID:Cell envelope of Neisseria gonorrhoeae: outer membrane and peptidoglycan composition of penicillin-sensitive and-resistant strains. 80 26

Highly purified preparations of cytoplasmic and outer membrane were isolated from aerobically grown Rhodospirillum rubrum lysed by sequential treatment with lysozyme, ethylenediaminetetraacetate, and Brij 58. The membranes were resolved and separated from other cellular constitutents by a combination of velocity and isopyknic sedimentation in sucrose density gradients. On the basis of their appearance in electron micrographs and their protein profiles in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, these preparations appear to be quite similar to those obtained from other gram-negative bacteria. The cytoplasmic membrane fraction contained the majority of the total membrane-bound succinic dehydrogenase activity and was 10-fold enriched in b- and c-type cytochrome with respect to the outer membrane. The latter fraction was characterized by a much greater carbohydrate content and the presence of arachidic acid, which is typical of R. rubrum lipopolysaccharide. Their protein fatty acid, and overall chemical compositions suggested that these preparations were freer from cross-contamination than those obtained from R. rubrum with currently available methods.
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PMID:Membranes of Rhodospirillum rubrum: isolation and physicochemical properties of membranes from aerobically grown cells. 82 Jun 89

Wild-type strains of the bacterial phytopathogen Erwinia amylovora (the cause of fire blight disease of apples and pears) are markedly susceptible to novobiocin, deoxycholate, and sodium dodecyl (= lauryl) sulfate. The inhibitory concentration, expressed as the concentration causing a 99% inhibition of growth, of these three antibacterial agents were 15 to 100, 40 to 800, and 50 to 800 mug/ml, respectively, depending on the E. amylovora strain. Growth of strains of other Erwinia spp. and Salmonella typhimurium is not affected at all, or is only slightly affected, at these concentrations. Introduction of the F'lac(+), RP1, and R100drd-56 (but not E-lac(+)) plasmids into an E. amylovora strain results in enhanced susceptibility to novobiocin and sodium dodecyl sulfate but not to deoxycholate. E. amylovora wild-type strains spontaneously release a periplasmic enzyme, cyclic phosphodiesterase, but not a cytoplasmic enzyme, glucose-6-phosphate dehydrogenase, into the growth medium. Addition of MgCl(2) (20 mM) and NaCl (84 mM) to tryptone broth stimulates the growth of wild-type E. amylovora strains and reduces or eliminates leakage of the periplasmic enzyme. Mutant strains of E. amylovora, selected for resistance to each separate antibacterial agent (or to all three of them), showed a direct correlation (in all but the novobiocin-resistant mutant) between drug resistance and reduced periplasmic leakiness. The relatively low maximum growth temperature (<37 degrees C) of E. amylovora seems unrelated to periplasmic leakage, as judged from the inability of added MgCl(2) to raise the maximum growth temperature, although the generation time at 30 degrees C is reduced from 108 to 54 min upon the addition of 20 mM MgCl(2). The extensive leakage of periplasmic enzyme and unusual drug susceptibility of E. amylovora strains might stem from some defect(s) in some cell envelope component(s) other than the lipopolysaccharide of these bacteria (which contain the usual liposaccharide constituents).
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PMID:Unusual susceptibility of Erwinia amylovora to antibacterial agents in relation to the barrier function of its cell envelope. 87 40

The lipopolysaccharide (LPS) of Chromatium vinosum has anticomplementary activity. This anticomplementary activity is destroyed by alkaline digestion of the LPS and is suppressed by both Mg2+ and Ca2+ ions. Treatment of the LPS with ethylenediaminetetraacetic acid, sodium deoxycholate, or dimethyl sulfoxide did not affect its toxicity toward mice; however, alkaline-treated LPS was not toxic. Treatment of the LPS with sodium deoxycholate, dimethyl sulfoxide, or sodium dodecyl sulfate resulted in reversible dissociation into subunits. Aggregation of the subunits into the original form was achieved by removing the dispersing agent by dialysis against distilled water followed by freezing and thawing. Electron micrographs of phenol-extracted LPS showed long filaments. Electron micrographs of sodium deoxycholate- and sodium dodecyl sulfate-treated and dialyzed LPS showed a mixture of small subunits and short filaments, whereas dimethyl sulfoxide-treated and dialyzed LPS contained only small ovoid spheres. The LPS produced an ordered series of multiple bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A similar banding pattern was observed for Salmonella abortus-equi and Proteus mirabilis LPS. The C. vinosum LPS appears to be mitogenic for mouse spleen cells.
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PMID:Biological and physicochemical properties of the lipopolysaccharide of Chromatium vinosum. 89 3

Selection for resistance to acriflavine in Streptococcus cremoris resulted in cross-resistance to the drugs neomycin, streptomycin, ethidium bromide, mitomycin C, and proflavine. Furthermore, the mutants showed resistance to lytic bacteriophages to which the parental strain was sensitive, and, unlike the parent, the mutants grew well at higher temperatures (40 degrees C). Revertants selected independently either for temperature sensitivity or for acriflavine sensitivity lost resistance to all the drugs and dyes but retained the bacteriophage resistance phenotype. The acriflavine-resistant mutation resulted in an increase in resistance by the bacterial cells to sodium dodecyl sulfate, a potent solvent of lipopolysaccharide and lipoprotein. It is suggested that the acriflavine resistance mutation determines the synthesis of a membrane substance resistant to higher temperatures.
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PMID:Acriflavine-resistant mutant of Streptococcus cremoris. 90 29

The optimal conditions for serum-free cultures of hamster lymphoid cells were determined. The cells responded to both the nonspecific thymus-derived lymphocyte mitogen concanavalin A (Con A) and the nonspecific bone marrow-derived lymphocyte mitogens lipopolysaccharide (LPS) and dextran sulfate (DxS). Normal MHA hamster serum was shown to specifically inhibit the response to LPS and DxS by 95% without inhibiting the response to Con A. The serum also did not inhibit one-way mixed lymphocyte reaction. Incubation of cells in 5% serum for short periods of time, followed by serum-free culture, did not lead to inhibition. The serum inhibited the LPS response by 65% even when added 24 h after initiation of the culture. The activity was associated with the high-molecular-weight material on Sephadex G-200 fractionation of serum. The inhibitory fraction did not possess antibody activity to LPS. The possibility that the material is an alpha2-macroglobulin is discussed.
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PMID:Serum-free culture of hamster lymphoid cells and differential inhibition of lipopolysaccharide stimulation by isologous serum. 97 57

Cell envelopes of Haemophilus influenzae have been prepared by breakage in a French pressure cell followed by differential centrifugation. The envelope fraction may be resolved into an inner-membrane (light) and an outer-membrane (heavy) fraction on density gradients. Envelopes from competent cells possess elevated levels of lipopolysaccharide with a composition different from that of log-phase cell envelopes. Three apparently new polypeptides have been observed in envelopes from competent cells by gel electrophoresis in sodium dodecyl sulfate; additional quantitative alterations in the profiles of membrane polypeptides also company the development of the capacity to transport deoxyribonucleic acid. Most of the polypeptide changes are confined to the outer membrane; one new polypeptide is associated with the inner cytoplasmic membrane of competent cells. Protein synthesis during competence developement is rquired for the change in lipopolysaccharides and in the envelope polypeptides to occur.
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PMID:Constitution of the cell envelope of Haemophilus influenzae in relation to competence for genetic transformation. 108 Apr 85

A substance which was mitogenic for murine B lymphocytes in the presence of 2-mercaptoethanol was isolated from agar. Stimulating activity of this material was stable to proteolysis or protein denaturants but was destroyed by periodate treatment. Agar-derived mitogen stimulation was distinct from that obtained with dextran sulfate or lipopolysaccharide and may define different populations of B lymphocytes.
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PMID:Growth of B-lymphocytes clones in semisolid culture is mitogen dependent. 108 21


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