Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The capsular polysaccharide (CP) of Bacteroides fragilis is an important virulence factor in the formation of experimental intraabdominal abscesses. Incubation of this organism with subinhibitory doses of clindamycin induced morphological changes in the bacteria, including elongation and loss of CP, detected by ferritin-labeled antibody to capsule. Pretreatment of bacteria with subinhibitory doses of clindamycin, however, did not affect the ability of live or heat-killed organisms to produce intraabdominal abscesses in a mouse model of intraabdominal sepsis. Dose-response experiments with purified CP as well as lipopolysaccharide (LPS) from B. fragilis ATCC strain 23745 mixed with sterile cecal contents as adjuvant revealed that both surface components of the organism were capable of causing abscesses in the mouse model. The dose of LPS required to induce abscesses was five times higher than the required dose of CP. Nevertheless, these studies suggested that B. fragilis LPS is another virulence factor in the formation of intraabdominal abscesses.
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PMID:Effect of subinhibitory doses of clindamycin on the virulence of Bacteroides fragilis: role of lipopolysaccharide. 371 90

Binding of either ferritin (F) or cationized ferritin (CF) was employed to indicate the surface charge of the envelope of mainly two Salmonella typhimurium strains (395 MR10, a Rd-mutant, and LT2-M1, a UDP-galactose-4-epimerase-less mutant). Lowering the pH from 7 to 4 decreased binding of CF, but increased binding of F. At low concentrations, the distribution of CF on S. typhimurium 395 MR10 was in general random, with individual ferritin molecules often forming clusters of two or three particles. At ionic strengths of 0.25M NaCl, ferritin produced distinctive, larger clusters at relatively few sites (10-50/cell). Addition of galactose to cultures of growing S. typhimurium, LT2-M1 reduced the binding of CF in 1-10 min, and numerous ferritin-free areas became visible. Possibly this is caused by a pluri-focal reduction in the negative cell surface charge that was generated at the multiple sites of export of new, smooth-type lipopolysaccharide, which either exhibits lesser charge or masks a preexisting surface charge. Dividing cells may show unequal charges on the prospective daughter cells, and the difference in the capacity for ferritin adsorption of both daughter cells is sharply separated at the division site.
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PMID:Anionic sites on the envelope of Salmonella typhimurium mapped with cationized ferritin. 618 82

We investigated the pathogenesis of increased glomerular permeability in Balb/c mice after 5 weeks of administration of a polyclonal B cell activator (bacterial lipopolysaccharide). The glomerular transfer of anionic ferritin across the capillary walls and the urinary excretion of serum albumin served as probes of glomerular permeability; anionic groups of the glomerular basement membrane were assessed by the binding of cationized ferritin, and glomeruli were studied by light, immunofluorescence, and electron microscopy. The mice developed circulating immune complexes, proteinuria, and a proliferative glomerulonephritis, with mesangial and capillary loop deposits of immunoreactants. Increased transfer of anionic ferritin molecules occurred across capillary walls with and without demonstrable electron-dense deposits; detachments of visceral epithelium were not seen, and epithelial transport of anionic ferritin was negligible. Loss of anionic groups was extensive in glomerular capillary loops with and without associated electron-dense deposits. The findings indicate that an increase in glomerular permeability may precede the deposition of immunoreactants in the capillary wall; that filtration of macromolecules can occur across capillary walls with or without demonstrable immune deposits; and that loss of anionic groups of the glomerular basement membrane and enhanced filtration of macromolecules can occur in the absence of focal detachments of the visceral epithelium.
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PMID:Altered glomerular permeability in the early phase of immune complex nephritis. 622 69

Evidence for transient localization of newly synthesized lipopolysaccharide at the periplasmic face of the inner membrane has been obtained by immunoelectron microscopic techniques. Salmonella typhimurium galE mutants in which O-antigen synthesis is dependent on addition of exogenous galactose were employed, and the distribution and fate of pulse-synthesized O antigen was examined by indirect ferritin labeling with anti-O-antigen IgG of spheroplasts prepared by treatment with lysozyme/EDTA. O-reactive lipopolysaccharide appeared rapidly at the exposed periplasmic face of the inner membrane after addition of galactose and was rapidly depleted upon termination of the pulse. Control experiments showed that secondary redistribution of lipopolysaccharide from outer membrane did not occur under the conditions employed for spheroplast formation and immunolabeling, and the pulse-chase kinetics were consistent with those expected for an intermediate in translocation of lipopolysaccharide to the outer membrane. In addition, undecaprenol-linked O antigen was detectable at the periplasmic face of the inner membrane within 30 sec after addition of galactose to a galE deep rough double mutant, and it accumulated stably in that location. The mutation in synthesis of the lipopolysaccharide core in the deep rough strain prevents transfer of O-antigen chains from undecaprenol phosphate to lipopolysaccharide. The result suggests that attachment of O antigen to lipopolysaccharide occurs on the extracytoplasmic side of the inner membrane and supports the conclusion that lipopolysaccharide is translocated to the outer membrane from the periplasmic, rather than the cytoplasmic, face of the inner membrane.
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PMID:An intermediate step in translocation of lipopolysaccharide to the outer membrane of Salmonella typhimurium. 633 98

Rabbits were immunized with the enterobacterial common antigen (ECA)-immunogenic strain Escherichia coli F470. ECA-specific antiserum was obtained by absorbing the resulting antisera with the genetically closely related ECA-negative strain E. coli F1283. These two strains also served as positive and negative controls in the localization study of ECA in Yersinia enterocolitica strain 75, smooth and rough forms (Ye75S and Ye75R), by the indirect immunoferritin technique. Cells of Ye75S grown at 22 degrees C showed no labeling with ferritin after treatment with the ECA-specific antiserum and subsequent ferritin-conjugated goat anti-rabbit antibodies. If the cells were grown at 40 degrees C, however, most of the cells showed weak ferritin labeling. At this higher growth temperature, the lipopolysaccharide of this strain contains less O-specific chains (6-deoxy-L-altrose), as was shown in a previous study. The rough mutant Ye75R, which lacks O-specific chains completely, showed denser labeling with ferritin. These results indicate that ECA on the cell surface of Ye75S is covered by O-specific chains of the lipopolysaccharide if grown at 22 degrees C and is therefore not accessible to ECA antibodies. It becomes accessible, however, when O-chains are lacking (R mutants) or when they are reduced in size or amount (growth at 40 degrees C).
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PMID:Localization of enterobacterial common antigen in Yersinia enterocolitica by the immunoferritin technique. 702 35

Leukocyte migration inhibition (LMI) is a widely used in vitro correlate of delayed type hypersensitivity (DTH) in mammals. This report describes the development of a direct agarose LMI assay for studying DTH in avian species. Optimum demonstration of LMI was found with leukocytes isolated on a Ficoll-diatrizoate gradient solution. The agarose culture plates were maintained at pH 7.2-7.4 in a water-vapor saturated, 39 degrees C. incubator with 2% CO2 tension. Antigen specific LMI was demonstrated in chickens with DTH to purified protein derivative of Mycobacterium (PPD) and ferritin. A good comparison between LMI and DTH, as measured by the delayed wattle reaction (DWR), was demonstrated. The effect of bacterial lipopolysaccharide (LPS) on LMI was examined and LPS in microgram quantities was found to inhibit in vitro migration of chicken leukocytes. Contamination of antigen preparations with LPS is a probable explanation for occasional nonspecific inhibition of leukocyte migration since endotoxin is an almost ubiquitous contaminant of antigen preparations.
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PMID:Inhibition of chicken leukocyte migration in vitro: a direct agarose plate assay. 717 21

Immunoelectron microscopy was combined with partial characterization of isolated exopolysaccharide to study binding of soybean lectin by Rhizobium japonicum strain USDA 138. Lectin-binding activity resided in two forms of exopolysaccharide produced during growth: an apparently very high-molecular-weight capsular form and a lower-molecular-weight diffusible form. At low-speed centrifugation, the capsular form cosedimented with cells to form a viscous, white, cell-gel complex which was not diffusible in 1% agar, and the diffusible form remained in the cell-free supernatant. Electron microscopic observation of the cell-gel complex after labeling with soybean lectin-ferritin conjugate revealed that capsular polysaccharides, frequently attached to one end of the cells, were receptors for lectin. The outer membrane of the cell bound no lectin. Various preparations of exopolysaccharide isolated from the culture supernatant were tested for lectin binding, interaction with homologous somatic antigen, and the presence of 2-keto-3-deoxyoctonate and were chromatographed in Sepharose 4B and 6B gel beds. Lectin binding was restricted to a polysaccharide component designated as lectin-binding polysaccharide. This polysaccharide, as present in the cell-free culture supernatant, was a diffusible acidic polysaccharide devoid of 2-keto-3-deoxyoctonate, with a molecular weight of 2 X 10(6) to 5 X 10(6). It was concluded that the soybean lectin-binding component of R. japonicum is an extracellular polysaccharide and not a lipopolysaccharide and that the diffusible lectin-binding polysaccharide probably differs from the very high-molecular-weight lectin-binding polysaccharide of the loose capsule (slime) only in the degree of polymerization.
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PMID:Localization and partial characterization of soybean lectin-binding polysaccharide of Rhizobium japonicum. 719 4

A flagellar sheath protein of Vibrio cholerae CA401 (Inaba) was characterized. Purity of the preparation was indicated by a single band on polyacrylamide gel electrophoresis gels and on Ouchterlony plates prepared with antibody against crude sheath material. The sheath protein was composed of three polypeptides with minimal molecular weights of 61,500, 60,000, and 56,500. The presence of sheath protein on the flagellum as well as on the outer membrane of the cell was demonstrated by ferritin labeling experiments with antiserum. Sheath protein antibody reacted similarly in labeling experiments and agglutination tests with a classical Ogawa strain and two nonagglutinating V. cholerae isolates, indicating that the sheath protein may represent the common Vibrio H antigen. Antibody specific for lipopolysaccharide labeled the cell but not the sheathed flagellum, which demonstrated that the sheath is not a simple extension of the outer membrane of the cell.
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PMID:Characterization of a flagellar sheath protein of Vibrio cholerae. 738 May 41

Biosynthesis of nitric oxide (NO) from L-arginine modulates activity of iron-dependent enzymes, including mitochondrial acontiase, an [Fe-S] protein. We examined the effect of NO on the activity of iron regulatory factor (IRF), a cytoplasmic protein which modulates both ferritin mRNA translation and transferrin receptor mRNA stability by binding to specific mRNA sequences called iron responsive elements (IREs). Murine macrophages were activated with interferon-gamma and lipopolysaccharide to induce NO synthase activity and cultured in the presence or absence of NG-substituted analogues of L-arginine which served as selective inhibitors of NO synthesis. Measurement of the nitrite concentration in the culture medium was taken as an index of NO production. Mitochondria-free cytosols were then prepared and aconitase activity as well as IRE binding activity and induction of IRE binding activity were correlated and depended on NO synthesis after IFN-gamma and/or LPS stimulation. Authentic NO gas as well as the NO-generating compound 3-morpholinosydnonimine (SIN-1) also conversely modulated aconitase and IRE binding activities of purified recombinant IRF. These results provide evidence that endogenously produced NO may modulate the post-transcriptional regulation of genes involved in iron homeostasis and support the hypothesis that the [Fe-S] cluster of IRF mediates iron-dependent regulation.
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PMID:Biosynthesis of nitric oxide activates iron regulatory factor in macrophages. 750 26

Recently, it was reported that nitric oxide (NO) directly controls intracellular iron metabolism by activating iron regulatory protein (IRP), a cytoplasmic protein that regulates ferritin translation. To determine whether intracellular iron levels themselves affect NO synthase (NOS), we studied the effect of iron on cytokine-inducible NOS activity and mRNA expression in the murine macrophage cell line J774A.1. We show here that NOS activity is decreased by about 50% in homogenates obtained from cells treated with interferon gamma plus lipopolysaccharide (IFN-gamma/LPS) in the presence of 50 microM ferric iron [Fe(3+)] as compared with extracts from cells treated with IFN-gamma/LPS alone. Conversely, addition of the iron chelator desferrioxamine (100 microM) at the time of stimulation with IFN-gamma/LPS increases NOS activity up to 2.5-fold in J774 cells. These effects of changing the cellular iron state cannot be attributed to a general alteration of the IFN-gamma/LPS signal, since IFN-gamma/LPS-mediated major histocompatibility complex class II antigen expression is unaffected. Furthermore, neither was the intracellular availability of the NOS cofactor tetrahydrobiopterin altered by treatment with Fe(3+) or desferrioxamine, nor do these compounds interfere with the activity of the hemoprotein NOS in vitro. We demonstrate that the mRNA levels for NOS are profoundly increased by treatment with desferrioxamine and reduced by Fe(3+). The half-life of NOS mRNA appeared not to be significantly altered by administration of ferric ion, and NOS mRNA stability was only slightly prolonged by desferrioxamine treatment. Nuclear run-off experiments demonstrate that nuclear transcription of cytokine-inducible NOS mRNA is strongly increased by desferrioxamine whereas it is decreased by Fe(3+). Thus, this transcriptional response appears to account quantitatively for the changes in enzyme activity. Our results suggest the existence of a regulatory loop between iron metabolism and the NO/NOS pathway.
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PMID:Iron regulates nitric oxide synthase activity by controlling nuclear transcription. 752 Apr 77


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