UNIPROT:P43026 - FACTA Search

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)

Lysozyme (EC 3.2.1.17) complexes with extracted Pseudomonas aeruginosa LPS in two distinct stages. The initial stage does not produce turbidity detectable by nephelometry (measured as nephelos units (N) per time) but does permit low-speed sedimentation of the lysozyme-lipopolysaccharide (LPS) complex. This association is 100% disrupted by the action of 0.1 M Mg2+. Monovalent cations at equal ionic strength to the Mg2+ concentration used for these studies failed to alter significantly the lysozyme-LPS complex, indicating that the role of Mg2+ was not strictly an ionic one. The study of lysozyme-LPS complexes may provide a model system for investigating in vivo protein-LPS interactions.
...
PMID:Protein-lipopolysaccharide interactions. 1. The reaction of lysozyme with Pseudomonas aeruginosa LPS. 41 86

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.
...
PMID:Biological and physicochemical properties of the lipopolysaccharide of Chromatium vinosum. 89 3

Recently we reported that rapid killing of Escherichia coli by granulocytes or granulocyte fractions is accompanied by an equally rapid and discrete increase in permeability of the microbial envelope (Beckerdite, Mooney, Weiss, Franson, and Elsbach. 1974. J. Exp. Med. 140: 396-409). Most of this permeability-increasing activity (PI) is found in a crude granule preparation. PI is quantitatively recovered in a 23,000-g supernatant fraction (Sup II) after sulfuric acid extraction of granulocyte homogenates prepared in water. PI is nondialyzable, destroyed by pronase and trypsin, stable at 4degreesC for at least 2 mo, and destroyed by heating at 94degreesC. Anionic substances, such as heparin sulfate and isolated E. coli lipopolysaccharide, bind to and inhibit PI. PI has been purified up to 1,000-fold from homogenate in a yield of 50percent by acid extraction and carboxymethyl-Sephadex chromatography. Such purified fractions have bactericidal activity that equals that of disrupted granulocytes and Sup II, are similarly enriched with respect to granule-associated phospholipase, and protease activities. Whereas E. coli, sensitive to PI, binds or inactivates solubilized PI, a resistant strain of Serratia marcescens does not. Binding of PI to sensitive microorganisms seems to be necessary for expression of its biological activity since both the apparent binding to and the biological effect of PI on E. coli are completely blocked by 10-20 mM Mg2+ or Ca2+. Mg2+ or Ca2+ can reverse the effect on E. coli permeability produced by Sup II or the carboxymethyl-Sephadex fraction but not that produced by granulocyte homogenate. The close association of bactericidal, phospholipase A2, and permeability-increasing activities towards several gram-negative bacterial species suggests that they may be related.
...
PMID:Partial characterization and purification of a rabbit granulocyte factor that increases permeability of Escherichia coli. 108 9

In Escherichia coli and Salmonella typhimurium, the cell wall that contains both the outer membrane layer and the peptidoglycan layer acts as a barrier of the molecular sieve type for the penetration of uncharged saccharides (G. Decad, T. Nakae, and H. Nikaido (1974) Fed. Proc. 33, 1240). Here we examined which of the layers of the cell wall limited the size of the penetrating molecules, by studying the penetration of saccharides into (a) cells whose peptidoglycan layer had been destroyed by lysozyme treatment or growth in the presence of penicillin and (b) isolated outer membrane vesicles. We found that peptidoglycan-defective cells were similar to intact, plasmolyzed cells in that they allowed a partial penetration of stachyose (molecular weight 666), but essentially excluded saccharides with molecular weights higher than 900 to 1000. We also found that the isolated outer membrane acted as a penetration barrier for saccharides. These observations led us to conclude that the outer membrane, rather than peptidoglycan, sets the size limit for the penetration of uncharged, hydrophilic molecules through the E. coli or S. typhimurium cell wall. The isolated outer membrane, however, had an exclusion limit much higher than that found in intact cells. This "leakiness" could be decreased either by the use of mutants producing extremely deficient lipopolysaccharide, or by trypsin treatment of the isolated membrane followed by heating and slow cooling in the presence of Mg2+. We feel that these observations are consistent with the hypothesis that the resealing of the ruptured outer membrane during the isolation procedure is often incomplete, and that cracks and holes thus generated are responsible for the "leakiness" of the isolated membrane vesicles.
...
PMID:Outer membrane as a diffusion barrier in Salmonella typhimurium. Penetration of oligo- and polysaccharides into isolated outer membrane vesicles and cells with degraded peptidoglycan layer. 110 Jun 25

A method was developed for the reassembly of membranous vesicle from the sodium deoxycholate-dissociated outer membrane components of Escherichia coli. The removal of the detergent by dialysis and the presence of Mg2+ were essential for the reassembly. Membrane protein alone did not form any membranous structure. Closed membranous vesicles similar to the native outer membrane were reassembled only when protein was mixed with both lipopolysaccharide and phospholipid in deoxycholate solution and subsequently dialized. The membrane showed a distinct trilaminar structure with a center-to-center distance between two dark lines of 53 A, which is a characteristic of the native outer membrane. This characteristic trilaminar structure was shown to be due to the presence of lipopolysaccharide. Phospholipd was required for the vesicularization of membrane. Lipopolysaccharide and/or phospholipid formed a membranous structure in the absence of protein, while the morphology of their negatively stained sample was quite different from that of the native outer membrane unless the outer membrane protein was added to the reassembly mixture. The protein from the cytoplasmic membrane was unable to reform membranous vesicle with lipopolysaccharide and phospholipid, indicating that the reassembly system discriminated outer membrane proteins from cytoplasmic proteins.
...
PMID:In vitro reassembly of the membranous vesicle from Escherichia coli outer membrane components. Role of individual components and magnesium ions in reassembly. 110 79

The outer membrane of gram-negative bacteria provides the cell with an effective permeability barrier against external noxious agents, including antibiotics, but is itself a target for antibacterial agents such as polycations and chelators. Both groups of agents weaken the molecular interactions of the lipopolysaccharide constituent of the outer membrane. Various polycations are able, at least under certain conditions, to bind to the anionic sites of lipopolysaccharide. Many of these disorganize and cross the outer membrane and render it permeable to drugs which permeate the intact membrane very poorly. These polycations include polymyxins and their derivatives, protamine, polymers of basic amino acids, compound 48/80, insect cecropins, reptilian magainins, various cationic leukocyte peptides (defensins, bactenecins, bactericidal/permeability-increasing protein, and others), aminoglycosides, and many more. However, the cationic character is not the sole determinant required for the permeabilizing activity, and therefore some of the agents are much more effective permeabilizers than others. They are useful tools in studies in which the poor permeability of the outer membrane poses problems. Some of them undoubtedly have a role as natural antibiotic substances, and they or their derivatives might have some potential as pharmaceutical agents in antibacterial therapy as well. Also, chelators (such as EDTA, nitrilotriacetic acid, and sodium hexametaphosphate), which disintegrate the outer membrane by removing Mg2+ and Ca2+, are effective and valuable permeabilizers.
...
PMID:Agents that increase the permeability of the outer membrane. 140 89

The structural polymorphism of deep rough mutant lipopolysaccharide--in many biological systems the most active endotoxin--from Salmonella minnesota strain R595 was investigated as function of temperature, water content, and Mg2+ concentration. Differential scanning calorimetry was used to determine the amount of bound water and the enthalpy change at the beta<==>alpha gel to liquid crystalline acyl chain melting. The onset, midtemperature Tc, and completion of the beta<==>alpha phase transition were studied with Fourier-transform infrared spectroscopy. Synchrotron radiation X-ray diffraction was used to characterize the supramolecular three-dimensional structures in each phase state. The results indicate an extremely complex dependence of the structural behavior of LPS on ambient conditions. The beta<==>alpha acyl chain melting temperature Tc lying at 30 degrees C at high water content (95%) increases with decreasing water content reaching a value of 50 degrees C at 30% water content. Concomitantly, a broadening of the transition range takes place. At still lower water content, no distinct phase transition can be observed. This behavior is even more clearly expressed in the presence of Mg2+. In the lower water concentration range (< 50%) at temperatures below 70 degrees C, only lamellar structures can be observed independent of the Mg2+ concentration. This correlates with the absence of free water. Above 50% water concentration, the supramolecular structure below 70 degrees C strongly depends on the [LPS]:[Mg2+] ratio. For large [LPS]:[Mg2+] ratios, the predominant structure is nonlamellar, for smaller [LPS]:[Mg2+] ratios there is a superposition of lamellar and nonlamellar structures. At an equimolar ratio of LPS and Mg2+ a multibilayered organization is observed. The nonlamellar structures can be assigned in various cases to structures with cubic symmetry with periodicities between 12 and 16 nm. Under all investigated conditions, a transition into the hexagonal II structure takes place between 70 and 80 degrees C. These observations are discussed in relation to the biological importance of LPS as constituent of the outer membrane of gram-negative bacteria and as potent inducer of biological effects in mammals.
...
PMID:Phase diagram of deep rough mutant lipopolysaccharide from Salmonella minnesota R595. 148 8

To obtain nontoxic and highly immunogenic lipopolysaccharide (LPS) for immunization, we incorporated Neisseria meningitidis LPS into liposomes. Native LPS and its salts were incorporated by the method of dehydration-rehydration of vesicles or prolonged cosonication. The most complete incorporation of LPS into liposomes and a decrease in toxicity were achieved by the method of dehydration-rehydration of vesicles. Three forms of LPS (H+ form, Mg2+ salt, and triethanolamine salt) showed different solubilities in water, the acidic form of LPS, with the most pronounced hydrophobic properties, being capable of practically complete association with liposomal membranes. An evaluation of the activity of liposomal LPS in vitro (by the Limulus amoebocyte test) and in vivo (by monitoring the pyrogenic reaction in rabbits) revealed a decrease in endotoxin activity of up to 1,000-fold. In addition, the pyrogenic activity of liposomal LPS was comparable to that of a meningococcal polysaccharide vaccine. Liposomes had a pronounced adjuvant effect on the immune response to LPS. Thus, the level of anti-LPS plaque-forming cells in the spleens of mice immunized with liposomal LPS was 1 order of magnitude higher and could be observed for a longer time (until day 21, i.e., the term of observation) than in mice immunized with free LPS. The same regularity was revealed in a study done with an enzyme-linked immunosorbent assay. This study also established that antibodies induced by immunization belonged to the immunoglobulin M and G classes, which are capable of prolonged circulation. Moreover, liposomal LPS induced a pronounced immune response in CBA/N mice (defective in B lymphocytes of the LyB-5+ subpopulation). The latter results indicate that the immunogenic action of liposomal LPS occurs at an early age.
...
PMID:Toxicity and immunogenicity of Neisseria meningitidis lipopolysaccharide incorporated into liposomes. 150 Jan 96

The enzyme 3-deoxy-D-manno-octulosonic acid (Kdo) transferase is encoded by the kdtA gene of Escherichia coli and plays a key role in lipopolysaccharide biosynthesis. It transfers Kdo from CMP-Kdo to lipid A or its tetraacyldisaccharide-1,4'-bisphosphate precursor, lipid IVA. Using a strain that overproduces the transferase approximately 500-fold, we have purified the enzyme to near homogeneity. The subunit molecular mass is approximately 43 kDa. Activity is stimulated by Triton X-100, is maximal at pH 7, but does not require Mg2+. The apparent Km values for lipid IVA and CMP-Kdo are 52 and 88 microM, respectively. Vmax is 15-18 mumol/min/mg when both substrates are added near saturation at pH 8. The purified enzyme transfers 2 Kdo residues to lipid A precursors or analogs bearing four to six fatty acyl chains and a 4'-monosphosphate moiety. Activity is inhibited by polymixin B and Re endotoxin. At low Kdo concentrations small amounts of the intermediate, (Kdo)1-IVA, accumulate. When this substance is isolated and incubated with purified enzyme in the presence of CMP-Kdo, it is converted to (Kdo)2-IVA. Formation of (Kdo)1-IVA is also observed when purified enzyme is incubated with (Kdo)2-IVA and 5 mM CMP, demonstrating that Kdo transfer is reversible. In summary, Kdo transferase consists of a single bifunctional polypeptide that incorporates the 2 innermost Kdo residues common to all lipopolysaccharide molecules in E. coli.
...
PMID:Biosynthesis of endotoxins. Purification and catalytic properties of 3-deoxy-D-manno-octulosonic acid transferase from Escherichia coli. 157 28

The mechanism of uptake of aminoglycosides across the outer membrane of Escherichia coli was reevaluated. Porin-deficient mutants showed no alteration in gentamicin or kanamycin susceptibility. Furthermore, the influence of kanamycin on intrinsic tryptophan fluorescence of porin OmpF (Y. Kobayashi, and T. Nakae, Eur. J. Biochem. 151:231-236, 1985) was shown to be strongly influenced by protein concentration and EDTA. This led to the hypothesis that aminoglycoside-mediated increases and decreases in intrinsic tryptophan fluorescence were due to aggregation-disaggregation of OmpF mediated by interaction at a divalent cation binding site on OmpF. Gentamicin, kanamycin, and polymyxin B increased E. coli outer membrane permeability to the hydrophobic fluorescent compound 1-N-phenyl-naphthylamine (NPN) and the peptidoglycan-degrading enzyme lysozyme. Addition of Mg2+ blocked these permeabilizing activities. Furthermore, gentamicin and polymyxin B bound to Mg(2+)-binding sites on E. coli lipopolysaccharide, as determined in dansyl polymyxin displacement experiments. A polymyxin-resistant, lipopolysaccharide-altered pmr mutant of E. coli had a fourfold-lower MIC of gentamicin and kanamycin and was more poorly permeabilized to 1-N-phenylnaphthylamine than was its parent strain. These data were consistent with uptake of aminoglycosides across the E. coli outer membrane by the self-promoted uptake mechanism.
...
PMID:Interaction of aminoglycosides with the outer membranes and purified lipopolysaccharide and OmpF porin of Escherichia coli. 165 59

<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>