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)

A calmodulin-dependent nitric oxide synthase was significantly induced in the liver of rats treated intravenously with heat-killed Propionibacterium acnes and 5 days later with Escherichia coli lipopolysaccharide. The apparent calmodulin-dependent and -independent isozymes were separated by Mono Q column chromatography after their partial purification by 2',5'-ADP-agarose affinity chromatography. Both enzymes had a molecular weight of 125,000 as determined by SDS-polyacrylamide gel electrophoresis and required NADPH, tetrahydrobiopterin, and dithiothreitol as cofactors. Their activities were completely inhibited by the specific nitric oxide synthase inhibitors NG-monomethyl-L-arginine and N omega-nitro-L-arginine at 80 and 800 microM, respectively. The peptide maps of these two isozymes with lysylendopeptidase and their reverse-phase column chromatographic profiles were indistinguishable. In the presence of bovine calmodulin, the purified calmodulin-dependent isozyme behaved as a calmodulin-independent isozyme on Mono Q column chromatography. The purified calmodulin-independent isozyme was converted to a calmodulin-dependent isozyme by EDTA and EGTA. Calmodulin blot analysis using 125I-calmodulin showed that the two isozymes bound calmodulin equally efficiently.
 ...
PMID:Identification of inducible calmodulin-dependent nitric oxide synthase in the liver of rats. 128 Nov 57

Endotoxins may interfere with platelet aggregation by interacting with the platelet membrane. The aim of this study was to evaluate the effects of tetanus toxin, Salmonella typhimurium porin, and bacterial lipopolysaccharide (LPS) on platelet aggregation induced by ADP and thrombin in vitro. Spontaneous platelet aggregation and platelet aggregation induced by ADP and thrombin were measured. Our results show that Salmonella typhimurium porin and bacterial LPS enhanced human and rabbit platelet aggregation induced by ADP and thrombin. Tetanus toxin did not affect platelet aggregation.
 ...
PMID:Effects of tetanus toxin, Salmonella typhimurium porin, and bacterial lipopolysaccharide on platelet aggregation. 133 19

We have cloned a gene from a Salmonella typhimurium with the ability to complement the rfaC mutation (heptose-deficient lipopolysaccharide, sensitivity to rough-specific bacteriophages, and susceptibility to hydrophobic antibiotics). A 1018-base pair EcoRV-Tth111I fragment, subcloned into the pBluescriptKS+ vector to yield pKZ103, retains complementing activity. Nucleotide sequencing revealed an open reading frame corresponding to a protein of 317 amino acids (M(r) approximately 35,100). The plasmid pKZ103, which has a properly aligned T7 promoter, can overexpress a protein of M(r) = 31,000 when T7 RNA polymerase is supplied. An in vitro system was established for analysis of heptose addition to the precursor [4'-32P](KDO)2-IVA (Brozek, K. A., Hosaka, K., Robertson, A. D., and Raetz, C. R. H. (1989) J. Biol. Chem, 264, 6956-6966). Soluble fractions from wild-type or heptose-deficient rfa mutants were tested for their ability to convert [4'-32P](KDO)2-IVA to more polar substances. In wild-type extracts, these conversions required addition of ATP or ADP-heptose. In extracts of rfaC-, rfaD-, or rfaE-deficient strains, no polar products were observed with ATP. ADP-heptose restored synthesis in rfaD and rfaE but not rfaC extracts, indicating that rfaD and rfaE are involved in ADP-heptose formation. When the cloned rfaC gene was introduced into an rfaC-deficient mutant, extracts from such cells regained the ability to metabolize [4'-32P](KDO)2-IVA, showing that rfaC encodes the enzyme that attaches the proximal heptose to lipopolysaccharide.
 ...
PMID:The rfaC gene of Salmonella typhimurium. Cloning, sequencing, and enzymatic function in heptose transfer to lipopolysaccharide. 152 14

Transposon insertion, followed by screening, has allowed the identification of a set of genes, called htr, whose products are required for Escherichia coli growth at elevated temperatures. The htrB gene has been shown to map at 23.5 min on the E. coli genetic map. It codes for a very basic, hydrophobic, 35,000-Mr polypeptide, possessing a putative membrane-spanning domain. At the non-permissive temperature, htrB mutant bacteria stop dividing, followed by the formation of bulges and eventual lysis. The htrC gene maps at 90 min, is under sigma 32 regulation and codes for a 21, 130-Mr polypeptide. At 43 degrees C, htrC mutant bacteria gradually lyse, whereas at intermediate temperatures they filament extensively. Finally, the htrM gene maps at 81 min, is under sigma 32 regulation and codes for a 35,000-Mr polypeptide. The HtrM null phenotype included inability to grow above 42 degrees C, extreme mucoidness and sensitivity to bile salts, even at the permissive temperatures. The htrM gene is identical to the rfaD gene, whose product is required for the biosynthesis of the lipopolysaccharide precursor ADP-L-glycero-D-mannoheptose (Pegues et al., J. Bact., 1990, 172, 4652-4660).
 ...
PMID:Complex phenotypes of null mutations in the htr genes, whose products are essential for Escherichia coli growth at elevated temperatures. 165 98

The molecular mechanisms surrounding the toxicity and high mortality rate that accompany the release of bacterial lipopolysaccharide (LPS) are unclear, although its potent activity suggests that an amplification system is involved. Because previous studies suggest that a guanine-nucleotide-binding protein (G-protein) may participate in LPS action, we have evaluated the effects of LPS on GTPase activity in membranes isolated from macrophage (RAW 264.7) and fibroblast (B82L) cell lines. LPS induced substantial GTPase activation (200-300% above basal), and kinetic analyses indicated that the maximal LPS-stimulated increase in velocity is observed within 15 min, that it is a low-Km (for GTP) activity, that it can be enhanced by ammonium sulphate, and that it appears to be pertussis toxin-insensitive. Moreover, the LPS-enhanced GTPase activity was not antagonized by phosphatase/ATPase inhibitors such as p-nitrophenyl phosphate, ouabain, bafilomycin or N-ethylmaleimide, and in fact was potentiated by the addition of ATP or ADP. Conversely, the LPS precursor, lipid X, which can decrease the lethal effects of LPS, was found to dose-dependently inhibit the LPS-mediated stimulation of GTPase activity. Half-maximal inhibition was seen at the same lipid X/LPS ratio known to be effective in vivo, i.e. 1:1(w/w). These effects appear to be specific because other phospholipids, detergents and glycosides neither stimulated basal, nor inhibited LPS-induced, GTPase activity. These data suggest the involvement of a GTPase in LPS action, and indicate that lipid X may act to directly antagonize LPS at this level.
 ...
PMID:Bacterial lipopolysaccharide-stimulated GTPase activity in RAW 264.7 macrophage membranes. 185 66

Normal mouse embryo fibroblasts (MEF) are killed by treatment with low doses of interferon gamma (IFN-gamma) in combination with lipopolysaccharide (LPS). This cytotoxicity has previously been shown to represent an active suicidal reaction. Here we show that the time period between first contact with IFN-gamma/LPS (t = 0 h) and cell death (t = 48 h) can be separated into two distinct periods, during which glycolytic metabolism of glucose either has a positive (8-24 h) or a negative (30-48 h) effect on cytotoxicity. During the first period (8-24 h), withdrawal of glucose from the culture medium, or inclusion in the medium of the glycolytic inhibitors deoxy-D-glucose, NaF or iodoacetate, prevented later cell death. During the second period (30-48 h), withdrawal of glucose or supplementation of the culture medium with glycolytic inhibitors was no longer protective; instead it was a requirement for cell suicide to occur. Glycolytic activity during the first period was found to be increased twofold in LPS-treated MEF and almost threefold in IFN-gamma/LPS-treated MEF. A variety of agents were found both to protect cells against IFN-gamma/LPS-induced cytotoxicity and to inhibit increased glycolysis in these cells: glucocorticoids, the serine-type protease inhibitor N-acetyl-DL-phenylalanine-beta-naphthyl ester, the ADP-ribosylation inhibitors 3-aminobenzamide and nicotinamide, and the transcription and translation inhibitors actinomycin and cycloheximide. Mitochondrial function, although normal in LPS-treated cells, was markedly depressed in IFN-gamma/LPS-treated MEF. Specifically, malate- and succinate-driven respiration was found to be impaired. Furthermore, IFN-gamma/LPS-treated MEF contained one-third of the ATP level of LPS-treated MEF. Withdrawal of L-arginine from the culture medium prevented cell death in IFN-gamma/LPS-treated MEF. N-Methyl-L-arginine, which is an inhibitor of nitric oxide (NO.) biosynthesis from L-arginine, also inhibited cell death. In conclusion, we propose that cell death in our experiments is due to an L-arginine/glycolysis-dependent impairment of mitochondrial respiration.
 ...
PMID:Interferon-gamma/lipopolysaccharide-treated mouse embryonic fibroblasts are killed by a glycolysis/L-arginine-dependent process accompanied by depression of mitochondrial respiration. 193 71

Plasma levels of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) and the in vitro ability of platelets to aggregate and of monocytes to express procoagulant (tissue factor) activity (PCA) were evaluated in five patients who are homozygous for familial hypercholesterolemia (FH) before and after a single and a regular 5-month cholesterol removal by low density lipoprotein (LDL) apheresis. The biweekly procedure resulted in a 25% to 30% reduction (approximately 150 mg/dl) in total and LDL cholesterol (both were greater than 550 mg/dl at the beginning of the study). The basal levels of t-PA antigen and fibrinolytic activity before and after 10 minutes of venous stasis, basal PAI activity, and PAI-1 antigen were comparable to controls and were not affected by LDL apheresis. Likewise, regardless of the cholesterol removal, the PCA of freshly isolated monocytes and that of monocytes incubated with lipopolysaccharide did not differ from control values. Finally, the pre-apheresis sensitivity of platelets to adenosine diphosphate, arachidonic acid, and collagen was 1.5 to 2 times the normal value. This ratio was unchanged throughout the 5-month procedure. We conclude that fibrinolysis and monocyte PCA are normal in FH patients, whereas platelet aggregation is abnormally high, and none of these parameters is significantly affected by a 25% to 30% reduction in total and LDL cholesterol by LDL apheresis. Furthermore, our data suggest that removal of cholesterol from plasma by LDL apheresis is important for gaining insight into the mechanisms involved in the ischemic complications of arteriosclerosis in FH patients.
 ...
PMID:Hemostatic variables in homozygous familial hypercholesterolemia. Effect of regular plasma cholesterol removal by low density lipoprotein apheresis. 212 91

Upon exposure to the bacterial chemotactic peptide fMet-Leu-Phe, human neutrophils release lysozyme and generate superoxide anions (O2.-). The synthetic lipoamino acid N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteine (Pam3Cys), which is derived from the N-terminus of bacterial lipoprotein, when attached to Ser-(Lys)4 [giving Pam3Cys-Ser-(Lys)4], activated O2.- formation and lysozyme release in human neutrophils with an effectiveness amounting to about 15% of that of fMet-Leu-Phe. Palmitic acid, muramyl dipeptide, lipopolysaccharide and the lipopeptides Pam3Cys-Ala-Gly, Pam3Cys-Ser-Gly, Pam3Cys-Ser, Pam3Cys-OMe and Pam3Cys-OH did not activate O2.- formation. Pertussis toxin, which ADP-ribosylates guanine-nucleotide-binding proteins (G-proteins) and functionally uncouples formyl peptide receptors from G-proteins, prevented activation of O2.- formation by fMet-Leu-Phe and inhibited Pam3Cys-Ser-(Lys)4-induced O2.- formation by 85%. Lipopeptide-induced exocytosis was pertussis-toxin-insensitive. O2.- formation induced by Pam3Cys-Ser-(Lys)4 and fMet-Leu-Phe was enhanced by cytochalasin B, by a phorbol ester and by a diacylglycerol kinase inhibitor. Addition of activators of adenylate cyclase and removal of extracellular Ca2+ inhibited O2.- formation by fMet-Leu-Phe and Pam3Cys-Ser-(Lys)4 to different extents. Pam3Cys-Ser-(Lys)4 synergistically enhanced fMet-Leu-Phe-induced O2.- formation and primed neutrophils to respond to the chemotactic peptide at non-stimulatory concentrations. Our data suggest the following. (1) Pam3Cys-Ser-(Lys)4 activates neutrophils through G-proteins, involving pertussis-toxin-sensitive and -insensitive processes. (2) The signal transduction pathways activated by fMet-Leu-Phe and Pam3Cys-Ser-(Lys)4 are similar but not identical. (3) In inflammatory processes, bacterial lipoproteins and chemotactic peptides may interact synergistically to activate O2.- formation, leading to enhanced bactericidal activity.
 ...
PMID:Activation of superoxide formation and lysozyme release in human neutrophils by the synthetic lipopeptide Pam3Cys-Ser-(Lys)4. Involvement of guanine-nucleotide-binding proteins and synergism with chemotactic peptides. 216 Feb 37

The studies reported here probe the existence of a receptor-mediated mode of fibrin-binding by macrophages that is associated with the chemical change underlying the fibrinogen-fibrin conversion (the release of fibrinopeptides from the amino-terminal domain) without depending on fibrin-aggregation. The question is pursued by 1) characterization of binding in relation to fibrinopeptide content of both the intact protein and the CNBr-fragment comprising the amino-terminal domain known as the NDSK of the protein, 2) tests of competition for binding sites, and 3) photo-affinity labeling of macrophage surface proteins. The binding of intact monomers of types lacking either fibrinopeptide A alone (alpha-fibrin) or both fibrinopeptides A and B (alpha beta-fibrin) by peritoneal macrophages is characterized as proceeding through both a fibrin-specific low density/high affinity (BMAX congruent 200-800 molecules/cell, KD congruent to 10(-12) M) interaction that is not duplicated with fibrinogen, and a non-specific high density/low affinity (BMAX greater than or equal to 10(5) molecules/cell, KD greater than or equal to 10(-6) M) interaction equivalent to the weak binding of fibrinogen. Similar binding characteristics are displayed by monocyte/macrophage cell lines (J774A.1 and U937) as well as peritoneal macrophages towards the NDSK preparations of these proteins, except for a slightly weaker (KD congruent to 10(-10) M) high-affinity binding. The high affinity binding of intact monomer is inhibitable by fibrin-NDSK, but not fibrinogen-NDSK. This binding appears principally dependent on release of fibrinopeptide-A, because a species of fibrin (beta-fibrin) lacking fibrinopeptide-B alone undergoes only weak binding similar to that of fibrinogen. Synthetic Gly-Pro-Arg and Gly-His-Arg-Pro corresponding to the N-termini of to the alpha- and the beta-chains of fibrin both inhibit the high affinity binding of the fibrin-NDSKs, and the cell-adhesion peptide Arg-Gly-Asp does not. Photoaffinity-labeling experiments indicate that polypeptides with electrophoretically estimated masses of 124 and 187 kDa are the principal membrane components associated with specifically bound fibrin-NDSK. The binding could not be up-regulated with either phorbol myristyl acetate, interferon gamma or ADP, but was abolished by EDTA and by lipopolysaccharide. Because of the low BMAX, it is suggested that the high-affinity mode of binding characterized here would be too limited to function by itself in scavenging much fibrin, but may act cooperatively with other, less limited modes of fibrin binding.
 ...
PMID:Characterization of a mode of specific binding of fibrin monomer through its amino-terminal domain by macrophages and macrophage cell-lines. 216 52

A variety of receptor agonists activate cells by stimulating polyphosphoinositide hydrolysis. Increasing evidence supports the concept that receptor-stimulated phosphoinositide hydrolysis is mediated by a guanosine triphosphate binding protein, which in some cell systems is inhibited by pertussis toxin through ADP-ribosylation. The cross-linking of membrane immunoglobulin by antigen or anti-Ig stimulates phosphoinositide hydrolysis resulting in the formation of inositol phosphate and diacylglycerol which act as second messengers in initiating B lymphocyte activation. In this report, we demonstrate that anti-Ig-stimulated inositol phosphate formation is enhanced by the nonhydrolyzable guanosine triphosphate analogue, GppNHp, in permeabilized B lymphocytes and also inhibited by pretreatment of intact cells with pertussis toxin. This latter effect is associated with the pertussis toxin-catalyzed ADP-ribosylation of a 41-kDa membrane protein which is of the same molecular weight as the guanosine triphosphate binding protein reported to mediate receptor-stimulated phosphoinositide hydrolysis in other cellular receptor systems. B lymphocyte proliferation induced by agents such as lipopolysaccharide and PMA plus calcium ionophore, which activate cellular proliferation without stimulating phosphoinositide breakdown, is not inhibited by pertussis toxin. We conclude that anti-Ig activation of B lymphocytes contains pertussis toxin- and guanosine triphosphate-sensitive components which are involved in regulating phosphoinositide breakdown and initiating cellular activation.
 ...
PMID:Pertussis toxin inhibition of anti-immunoglobulin-stimulated proliferation and inositol phosphate formation. 217 54


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