UNIPROT:P43026 - FACTA Search

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

Peripheral blood monocytes obtained from 8 colorectal cancer patients and 6 normal controls were incubated in vitro with interferon-r (IFN-r) in the presence of bacterial lipopolysaccharide (LPS). The cytotoxic properties of the monocyte were determined subsequent to the interaction with radiolabeled autologous, allogeneic, as well as cultured colorectal cancer cells. Monocytes from normal controls and all colorectal cancer patients were activated in vitro to become tumoricidal; monocytes lysed tumorigenic cells but not nontumorigenic cells. Activators of protein kinase C (e.g. phorbol esters, PMA) and Ca2+ ionophores (A23187) when added alone did not effect the activation state of the monocyte. Whereas, PMA and A23187 cooperatively reproduced the ability of IFN-r to prime monocytes for tumoricidal activity. In the presence of PMA, A23187, and EGTA, the addition of excessive Ca2+ was sufficient for priming, whereas the addition of excessive Mg2+ was much less efficient. Priming by IFN-r, however, was not blocked by EGTA. An efflux of Ca2+ from preloaded monocytes was significantly increased by A23187 and by IFN-r. Quin-2/AM, an intracellular chelator of Ca2+, blocked priming by IFN-r. The results suggest that priming of monocytes for tumoricidal function by IFN-r may be involved in the activation of protein kinase C and mobilization of intracellular Ca2+.
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PMID:Tumoricidal activity of interferon-r activated peripheral monocytes in colorectal cancer patients. 171 83

Monoclonal antibody (mAb) probes were used to investigate the expression of lipopolysaccharide (LPS) on four Escherichia coli strains, grown under a variety of conditions in batch culture which mimicked some of the in vivo environmental conditions of an infected host. Techniques of silver staining, immunoblotting, whole cell ELISA and flow cytometry were all used to monitor the expression of LPS on the bacteria and the binding of the anti-LPS mAbs. Growth in heat-inactivated sheep serum and magnesium-depleted conditions demonstrated increased expression of LPS core and subsequent increased binding of anti-core mAbs. Magnesium-depleted conditions also resulted in decreased production of O-polysaccharide material. Iron-depleted bacteria showed only minor changes in LPS expression, although increased binding of anti-core mAbs was observed. Nitrogen-deficient/high-carbon conditions, chosen to promote capsule production, resulted in increased expression of O-polysaccharide and decreased binding of anti-core mAbs.
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PMID:Monoclonal antibodies as probes for detecting lipopolysaccharide expression on Escherichia coli from different growth conditions. 172 64

Campylobacter fetus strains may be of serotype A or B, a property associated with lipopolysaccharide (LPS) structure. Wild-type C. fetus strains contain surface array proteins (S-layer proteins) that may be extracted in water and that are critical for virulence. To explore the relationship of S-layer proteins to other surface components, we reattached S-layer proteins onto S- template cells generated by spontaneous mutation or by serial extractions of S+ cells with water. Reattachment occurred in the presence of divalent (Ba2+, Ca2+, Co2+, and Mg2+) but not monovalent (H+, NH4+, Na+, K+) or trivalent (Fe3+) cations. The 98-, 125-, 127-, and 149-kDa S-layer proteins isolated from strains containing type A LPS (type A S-layer protein) all reattached to S- template cells containing type A LPS (type A cells) but not to type B cells. The 98-kDa type B S-layer protein reattached to SAP- type B cells but not to type A cells. Recombinant 98-kDa type A S-layer protein and its truncated amino-terminal 65- and 50-kDa segments expressed in Escherichia coli retained the full and specific determinants for attachment. S-layer protein and purified homologous but not heterologous LPS in the presence of calcium produced insoluble complexes. By quantitative enzyme-linked immunosorbent assay, the S-layer protein copy number per C. fetus cell was determined to be approximately 10(5). In conclusion, C. fetus cells are encapsulated by a large number of S-layer protein molecules which may be specifically attached through the N-terminal half of the molecule to LPS in the presence of divalent cations.
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PMID:Reattachment of surface array proteins to Campylobacter fetus cells. 173 16

Overexpression of major outer membrane protein OprH of Pseudomonas aeruginosa as a result of mutation (in strain H181) or adaptation to low Mg2+ concentrations (in parent strain H103) is accompanied by increased resistance to polymyxin B, gentamicin, and EDTA. A 2.8-kb EcoRI fragment containing the oprH gene was subcloned into several different expression plasmids in Escherichia coli. These experiments showed that significant levels of OprH could be produced from a promoter on the EcoRI fragment; that the cloned oprH gene was not regulated by Mg2+ deficiency; that there were no differences in the expression of OprH in any construction, regardless of whether the gene from strain H103 or its OprH-overexpressing, polymyxin B-resistant derivative, strain H181, was used; and that overexpression of OprH in E. coli to the level observed in P. aeruginosa H181 did not result in a resistance phenotype. These results favored the conclusion that the mutation in strain H181 was a regulatory rather than a promoter mutation. The oprH gene was cloned behind the benzoate-inducible pm promoter in plasmid pGB25 and transferred to P. aeruginosa H103. Overexpression of OprH from the cloned gene in H103/pGB25 resulted in EDTA resistance but not polymyxin B resistance. This result suggested that another factor, possibly lipopolysaccharide, was affected by the mutation in strain H181. Consistent with this suggestion was the demonstration that mutants of strain H181 with alterations in lipopolysaccharide had reverted to wild-type polymyxin B susceptibility but had unaltered gentamicin and EDTA resistance. These data were consistent with the hypothesis that OprH replaces outer membrane-stabilizing divalent cations.
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PMID:Pseudomonas aeruginosa outer membrane protein OprH: expression from the cloned gene and function in EDTA and gentamicin resistance. 193 72

We have reported here on the structural polymorphism of lipid A, the "endotoxic principle" of bacterial lipopolysaccharide. For lipid A of rough mutant lipopolysaccharide from Salmonella minnesota and Escherichia coli, the three-dimensional supramolecular structures were determined with x-ray diffraction utilizing synchrotron radiation. The investigations were performed in the water concentration range 10 to 95% by weight, at [lipid A]:[Mg2+] molar ratios from 1:0 to 0.1:1, and in the temperature range from 20 to 70 degrees C. These data were correlated with measurements of the beta----alpha phase behaviour which was monitored with differential scanning calorimetry and Fourier-transform infrared spectroscopy. We found that the transition temperature of the acyl chains ranges--in the absence of Mg2(+)-from 45 degrees C at high to 56 degrees C at low water content, and-at an equimolar content of Mg2(+)-from 52 degrees C at high to 59 degrees C at low water concentrations. In the gel phase-in which the lipid A acyl chains are more disordered than those from saturated phospholipids-cubic phases are adopted at high water content (greater than 60%) and at high [lipid A]:[Mg2+] molar ratios. At low water contents, lamellar states are assumed exclusively. In the liquid crystalline state of lipid A, the hexagonal HII state is adopted under all conditions. The structural variability of lipid A is highest at high water concentrations, and structural changes may be induced by only slight changes in temperature, water content, and Mg2+ concentration. Under physiological conditions, however, the lipid A assemblies exhibit a strong preference to cubic structures.
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PMID:Phase diagram of lipid A from Salmonella minnesota and Escherichia coli rough mutant lipopolysaccharide. 210 Jan 44

The R-form lipopolysaccharide (LPS) from Klebsiella pneumoniae strain LEN-111 (03-:Kl-), from which cationic material had been removed by electrodialysis, formed an orderly hexagonal lattice structure when suspended in 50 mM Tris buffer at pH 8.5 containing MgCl2. The center-to-center distance (lattice constant) of the hexagonal lattice structure depended upon the concentration of MgCl2 and reached the shortest value (15 nm) at 10 mM. In contrast, CaCl2 could not produce the orderly hexagonal lattice structure but produced an irregular network structure with a center to center distance of 19 to 20 nm. When the LPS was suspended in Tris buffer containing 10 mM MgCl2 mixed with 1 or 10 mM CaCl2, formation of the orderly hexagonal lattice structure of the magnesium salt type was inhibited and the LPS showed the structure of the calcium salt type. When 1 or 10 mM CaCl2 was mixed with 10 mM MgCl2, the binding of Mg to the LPS was significantly inhibited compared with when 10 mM MgCl2 was added alone. On the contrary, when 10 mM CaCl2 was mixed with 10 mM MgCl2, the binding of Ca to the LPS was enhanced compared with when 10 mM CaCl2 was added alone. It was therefore concluded that the inhibition of formation of the hexagonal lattice structure of the magnesium salt type by addition of CaCl2 is due to the inhibition of the binding of Mg to the LPS. Such a competitive interaction of Mg2+ and Ca2+ was also observed with the electrodialyzed LPS of Escherichia coli K-12.
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PMID:Interaction of Mg2+ and Ca2+ in in vitro hexagonal assembly of R-form lipopolysaccharides. 218 53

The phase behaviour, particularly the fluidity within each phase state and the transitions between them, of lipopolysaccharides and of their lipid moiety, free lipid A, of various species of Gram-negative bacteria, especially of Salmonella minnesota and Escherichia coli, has been investigated by applying mainly Fourier-transform infrared spectroscopy and differential scanning calorimetry. For enterobacterial strains, the transition temperatures of the gel----liquid crystalline (beta----alpha) phase transition of the hydrocarbon chains in dependence on the length of the sugar moiety are highest for free lipids A (around 45 degrees C) and lowest for deep rough mutant lipopolysaccharides (around 30 degrees C). Evaluating certain infrared active vibration bands of the hydrocarbon moiety, mainly the symmetric stretching vibration of the methylene groups around 2850 cm-1, it was found that, in the gel state, the acyl chains of lipopolysaccharides and free lipid A have a higher fluidity as compared with saturated and the same fluidity as compared with unsaturated phospholipids. This 'partial fluidization' of lipopolysaccharide below the transition temperature correlates with its reduced enthalpy change at that temperature compared to phospholipids with the same chain length. The fluidity depends strongly on ambient conditions, i.e. on the Mg2+ and H+ content: higher Mg2+ concentrations and low pH values make the acyl chains of free lipid A and lipopolysaccharide preparations significantly more rigid and also partially increase the transition temperature. The influence of Mg2+ is highest for free lipid A and decreases with increasing length of the sugar side chain within the lipopolysaccharide molecules, whereas the effect of a low pH is similar for all preparations. At basic pH, a fluidization of the lipopolysaccharide and lipid A acyl chains and a decrease in transition temperature take place. Free lipid A and all investigated rough mutant lipopolysaccharides exhibit an extremely strong lyotropic behaviour in the beta----alpha melting enthalpy but not in the value of the transition temperature. The phase transition is distinctly expressed only at water concentrations higher than 50-60%. A further increase of the water content still leads to an increase in the phase-transition enthalpy, particularly for lipopolysaccharides with a more complete sugar moiety. The fluidity of the hydrocarbon chains is shown to be an important parameter with respect to the expression of biological activities.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Investigation into the fluidity of lipopolysaccharide and free lipid A membrane systems by Fourier-transform infrared spectroscopy and differential scanning calorimetry. 219 98

When the R-form lipopolysaccharide (LPS) from Klebsiella pneumoniae strain LEN-111 (O3-:K1-), from which cationic material had been removed by electrodialysis, was suspended in 50 mM Tris buffer at pH 8.5 containing 0.1 mM or higher concentrations of MgCl2, it formed an ordered two-dimensional hexagonal lattice structure and its center-to-center distance (lattice constant) depended upon the concentration of MgCl2 and reached the shortest value (14 nm) at 10 mM. In contrast, in the presence of 0.1 to 10 mM CaCl2 in place of MgCl2, the electrodialyzed LPS did not form such an ordered hexagonal lattice structure but formed an irregular network structure with a center-to-center distance of 19 to 20 nm. We investigated interaction of Mg2+ and Ca2+ in formation of the hexagonal lattice structure by the electrodialyzed LPS suspended in 50 mM Tris buffer at pH 8.5. When 0.1 mM or higher concentrations of CaCl2 were mixed with 1 mM MgCl2 or when 1 mM or higher concentrations of CaCl2 was mixed with 10 mM MgCl2, the electrodialyzed LPS did not form the hexagonal lattice structure of the magnesium salt type but formed the irregular network structure of the calcium salt type. In the coexistence of equimolar or higher concentrations of CaCl2 together with 1 or 10 mM MgCl2, the binding of Mg to the electrodialyzed LPS was significantly inhibited and, conversely, the binding of Ca was enhanced as compared with when MgCl2 or CaCl2 was present alone. However, the coexistence of 10 times less molar concentrations of CaCl2 did not significantly inhibit the binding of Mg to the electrodialyzed LPS. Therefore, the inhibition of formation of the Mg2(+)-mediated hexagonal lattice structure of the electrodialyzed LPS by equimolar or higher concentrations of CaCl2 accompanied the inhibition of binding of Mg but that by 10 times less molar concentrations of CaCl2 did not accompany it.
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PMID:Inhibitory effect of Ca2+ on formation of Mg2(+)-mediated two-dimensional hexagonal lattice structure by an R-form lipopolysaccharide from Klebsiella pneumoniae. 220 90

The effect of phosphorylation of pre interleukin 1 alpha (IL 1 alpha) on its association with various phospholipids was investigated. We prepared genetically engineered truncated human pre IL 1 alpha (residues 64 to 271) and phosphorylated this pre IL 1 alpha in vitro by using the catalytic subunit of cAMP-dependent protein kinase. Phosphorylated truncated pre IL 1 alpha selectively binds to acidic phospholipids including phosphatidic acid, phosphatidylserine, and phosphatidylinositol, but not to other phospholipids (phosphatidylcholine and phosphatidylethanolamine). This binding required divalent cations: Ca2+ or Mn2+, but not Mg2+. In order to obtain half-maximal binding of pre IL 1 alpha to phosphatidic acid or phosphatidylserine, Ca2+ between 5 and 100 microM was required. Unphosphorylated pre IL 1 alpha did not bind to phosphatidylserine, indicating that phosphorylation is required for this binding. Phosphorylated pre IL 1 alpha did not bind to intact peripheral blood mononuclear cells irrespective of lipopolysaccharide stimulation, but did bind to membrane vesicles prepared from these cells in the presence of calcium. Furthermore, phosphorylated pre IL 1 alpha bound only to inside-out ghosts, but not right-side-out ghosts, prepared from human red blood cells. Taken together, these data suggest that phosphorylated pre IL 1 alpha binds to the inner surface of plasma membrane in a Ca2(+)- and phospholipid-dependent manner.
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PMID:Calcium-dependent binding of phosphorylated human pre interleukin 1 alpha to phospholipids. 239 32

We examined the mechanisms involved in neutrophil adherence to cultured human umbilical vein endothelial cells (HEC) induced by direct stimulation of the neutrophils by phorbol myristate acetate (PMA), formylmethionyl-leucyl-phenylalanine (FMLP), or the calcium ionophore A23187 (neutrophil-dependent adherence), or by pretreatment of HEC with interleukin-1 (IL-1), tumour necrosis factor (TNF) or lipopolysaccharide (LPS) (endothelial-dependent adherence). Two distinct mechanisms for neutrophil adherence to HEC were demonstrated by performing adherence assays: (i) at 37 degrees versus 4 degrees; (ii) in the presence of Ca2+ only versus Mg2+ only; and (iii) in the presence or absence of monoclonal antibodies (mAb) to the CD11/CD18 adhesion complex of neutrophils. A CD11/CD18-dependent mechanism (i.e. inhibited by anti-CD18 mAb) was identified that was active in the presence of Mg2+ only but not of Ca2+ only, and at 37 degrees but not at 4 degrees. A CD11/CD18-independent mechanism (i.e. not inhibited by anti-CD18 mAb) was active at 4 degrees and at 37 degrees, and in the presence of Ca2+ only and of Mg2+ only. Neutrophil-dependent adherence induced by FMLP or PMA occurred solely via the CD11/CD18-dependent mechanism, whereas endothelial-dependent adherence induced by a 4-hr pretreatment with IL-1, TNF, or LPS involved both CD11/CD18-dependent and/independent mechanisms. CD11/CD18-deficient neutrophils isolated from a patient with leucocyte adherence deficiency (LAD) maintained the ability to adhere to LPS-pretreated HEC in the presence of Ca2+ only, indicating that this mechanism of adherence involves a receptor on the neutrophil distinct from CD11/CD18. Furthermore, the disappearance of the CD11/CD18-independent, but not of the CD11/CD18-dependent mechanism of adherence, in HEC treated with TNF for 24 hr suggests that the two mechanisms of neutrophil adherence also involve distinct inducible endothelial-leucocyte adhesion molecules (E-LAM).
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PMID:CD11/CD18-independent neutrophil adherence to inducible endothelial-leucocyte adhesion molecules (E-LAM) in vitro. 257 36

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