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

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

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

The separation of inner and outer membrane of Rhodopseudomonas spheroides has been achieved by means of sucrose density gradient (20%, 40%, 60%, w/w) centrifugation. The upper fraction of the gradient, with a specific density 1.181 (g/cm3), is high in cytochrome and succinate dehydrogenase activities, low in lipopolysaccharides and it is designated the inner membrane fraction. The bottom fraction of the gradient, with a specific density 1.240, is high in lipopolysaccharide and contains neither cytochrome nor succinate dehydrogenase activities. This fraction is the cell wall or outer membrane fraction. The intermediate band on the gradient is an unseparated fraction of inner and outer membrane fragments. This fraction has a specific denisty of 1.211 and represents less than 3% of total crude envelope. Thin sections of the vesicles of the inner membrane fraction and those of outer membrane provide morphological evidence for the identity of the individual membrane fractions. At least 22 protein bands are resolved by employing sodium dodecyl sulfate slab gel electrophoresis. Six bands are present only in the inner membrane and two bands are found exclusively in the outer membrane. Most of the remaining polypeptides are present in greater amounts in the inner membrane relative to the outer membrane fractions.
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PMID:Separation of inner and outer membranes of Rhodopseudomonas spheroides. 108 79

1. The crude envelope preparation obtained by sonication of Proteus mirabilis cells in the presence of lysozyme was separated into outer and cytoplasmic membrane fractions by sucrose density gradient centrifugation. The outer membrane fraction accounted for about two thirds of the dry weight of the envelope preparation. 2. In thin sections, the outer and cytoplasmic membrane fractions were shown to consist of vesicles bounded by a single trilaminar membrane, but those of the outer membrane were considerably smaller and were frequently open, forming C-shaped structures. The cytoplasmic membrane vesicles were cleaved by freeze fracturing to expose fracture faces studded with particles, while the outer membrane fragments resisted cleavage. 3. The outer membrane fraction consisted of protein (similar to 40%), lipopolysaccharide (similar to 36%) and lipid (similar to 18%) and had a density of about 1.22 g/cm3. The cytoplasmic membrane fraction consisted mostly of protein (similar to 56%) and lipid (similar to 38%), had a density of about 1.16 g/cm3, and contained almost all the NADH oxidase, succinate and D-lactate dehydrogenase activities of the crude envelope preparation. 4. Electrophoresis in polyacrylamide gels containing sodium dodecylsulfate revealed over 20 polypeptide bands in the cytoplasmic membrane fraction and only 6-7 in the outer membrane fraction. The outer membrane electrophorogram was dominated by a major band (mol. wt 40 000) which was resolved into two bands when electrophoresed in an acidic gel system. Amino acid analysis revealed a higher content of polar amino acids in the protein moiety of the outer membrane.
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PMID:The outer membrane of Proteus mirabilis. I. Isolation and characterization of the outer and cytoplasmic membrane fractions. 109 Dec 89

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.
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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

Protein II*, one of the major Escherichia coli outer cell envelope membrane proteins has been characterized. The protein is heat-modifiable and perhaps due to complete unfolding and/or binding of sodium dodecylsulfate only at higher temperatures the modified protein exhibits a higher apparent molecular weight (33,000) than the non-modified form (28,000). Protein-chemical evidence as well as the behavior of two mutant proteins II* very strongly suggest that this protein consists of a single polypeptide chain and that in the strains studied there is no other major protein with similar characteristics. For another outer membrane protein, protein III (molecular weight 17,000), it has not yet been established if it should be classified as a major protein. Protein III consists of one or perhaps two polypeptide chains. The possibility existed that protein III is bound covalently to lipopolysaccharide, and this has been ruled out. Also, the lipopolysaccharide of the E. coli strains studied does not carry covalently bound protein in amounts anywhere near stoichiometry. N-on-protein substituents were neither found in protein II* nor in protein III. It is concluded that in E. coli B/r and the E. coli K12 strains used there are three major proteins: I, II, and IV; protein III may also belong to this class. There are not more major proteins than these. All four proteins are compared and discussed regarding their unknown functions and their relation to E. coli outer membrane proteins studied by other authors.
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PMID:The major proteins of the Escherichia coli outer cell envelope membrane. Characterization of proteins II* and III, comparison of all proteins. 110 24

Lipopolysaccharide preparations from R(rough) Escherichia coli O8-,SR(semirough) Salmonella typhimurium and S (smooth) strains E. coli O8 and Citrobacter 396 were disintegrated with sodium dodecylsulfate and subjected to polyacrylamide gel electrophoresis in the presence of 1% sodium dodecylsulfate. The results obtained were compared with those obtained from the same lipopolysaccharide preparations by degradation analysis. In dodecylsulfate gel electrophoresis the lipopolysaccharide preparation from the E. coli R mutant and the S. typhimurium SR mutant showed one band each (R-and SR-band, respectively) with different electrophoretic mobilities. The lipopolysaccharide preparations from the E. coli O8-strain exhibited two bands, one of which had the same electrophoretic mobility as the R-band and the other was identified as S-band. The lipopolysaccharide preparation from the Citrobacter 396-S-strain exhibited four bands: one R-band, one SR-band and two S-bands. The results showed that wild-type S strains contain more than one type of lipopolysaccharide. They differ in the length of their O-specific polysaccharide chains. The lipid A content of the different lipopolysaccharide was expressed in their electrophoretic mobilities.
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PMID:Heterogeneity of lipopolysaccharides. Analysis of polysaccharide chain lengths by sodium dodecylsulfate-polyacrylamide gel electrophoresis. 110 34

Envelope proteins of one smooth (S) strain and seven rough (R) mutants of Salmonella minnesota were examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. All strains gave similar band patterns although some consistent differences were detected. A major polypeptide band at 54k, which coincided with the flagellar component, was more prominent in S, Ra and Rb than in the Rc, Rd and Re chemotypes. The latter strains, however, showed more prominent bands at 48, 19 and 18k. The stage of growth at which the cultures were harvested was also found to affect the band patterns, particularly in the 54 and 40k regions. A closer examination of S, Ra and Re strains suggested that the levels of the major 40 and 37k bands were slightly reduced in Re. It is concluded that the progressive loss of lipopolysaccharide components which occurs from the S chemotype through various degrees of roughness to Re is accompanied by a change in the envelope protein composition, apparently between Rb and Rc.
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PMID:Envelope proteins in Salmonella minnesota mutants. 115 43

The analysis of the components of a bacterium may be envisaged from the biological aspect (fractionation), the ultrastructural aspect (staining of the structures examined electron-microscopically), and the biological aspect (measure of an activity). In this report we attempt to examine the components of brucella from all three aspects simultaneously. The brucella envelopes have the same ultrastructure as that of gramnegative bacteria: outer membrane, thick stratum or peptidoglycane, periplasmic space, cytoplasmic membrane. The outer membrane of brucella in phase S contains many types of polysaccharides: (1) the lipopolysaccharide (LPS) (S) and polysaccharide B are solubilized by the phenol-uater and ether-water methods, by trichloracetic acid (TCA), by heated sodium dodecyl-sulfate (SDS). The exact localization of polysaccharide B is not known; by the phenol-water extraction method, the LPS (S) in its toxic form (endotoxin) passes in solution into the phenol phase, unlike the endotoxin of enterobacteria, which passes into the aqueous phase. In addition to its toxicity, this LPS (S) is responsible for reactions of immediate hypersensitivity as well as serological reactions towards the standard antigen. It presents A + M antigenic sites; (2) one or more of the polysaccharides remains unsolubilized by the ether-water method, but solubilized by heated SDS; (3) a polysaccharide is linked to peptidoglycane. The structure of the outer membrane of the brucella in phase R is analogous to that of LPS, carrying antigen R, characteristic of these strains. This antigen may be utilized for the serological diagnosis of infections due to brucella R (B. ovis) or vaccinations by a vaccine in phase R. The peptidoglycane fraction extracted by the heated SDS has a more complex structure than that of E. coli: it consists of a supplementary outer layer containing amino acids and polysaccharides. This fraction has a vaccinal activity. A soluble protein fraction, without organized structure, no doubt of cytoplasmic origin, may be extracted by a cold saline solution. This fraction, known as "brucelline", reveals delayed hypersensitivity when injected intradermally. The biological activity of the other structures (periplasm, cytoplasmic membrane, ribosomes...) is not known. Biological activities have been attributed to fractions, but since these are badly defined from the structural point of view it is difficult to determine the connection between activities and structures.
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PMID:[Structure and constituents of Brucella. Characterization and biological properties of the fractions]. 126 52

Corticosteroids are the preeminent antiinflammatory agents although the molecular mechanisms that impart their efficacy have not been defined. The endothelium plays a critical role in inflammation by directing circulating leukocytes into extravascular tissues by expressing adhesive molecules for leukocytes [e.g., endothelial-leukocyte adhesion molecule 1 (ELAM-1) and intercellular adhesion molecule 1 (ICAM-1)]. We therefore determined whether corticosteroids suppress inflammation by inhibiting endothelial expression of adhesion molecules for neutrophils (polymorphonuclear leukocytes). Preincubation of endothelial cells with endotoxin [lipopolysaccharide (LPS), 1 microgram/ml] led to a 4-fold increase in subsequent adherence of polymorphonuclear leukocytes (P < 0.0001, n = 10) to endothelial cells, an increase that was markedly attenuated when endothelial cells were treated with dexamethasone (IC50 < 1 nM, P < 0.0001, n = 6 or 7) during preincubation with LPS. Moreover, the steroid receptor agonist cortisol (10 microM), but not its inactive metabolite tetrahydrocortisol (10 microM), diminished LPS-induced endothelial cell adhesiveness. Further evidence that the action of dexamethasone was mediated through ligation of corticosteroid receptors [human glucocorticoid receptors (hGRs)] was provided by experiments utilizing the steroid antagonist RU-486. RU-486 (10 microM), which prevents translocation of ligated hGR to the nucleus by inhibiting dissociation of hGR from heat shock protein 90, completely aborted the effect of dexamethasone on adhesiveness of endothelial cells (P < 0.0005, n = 3). Treatment of endothelial cells with LPS (1 microgram/ml) stimulated transcription of ELAM-1, as shown by Northern blot analysis, and expression of membrane-associated ELAM-1 and ICAM-1, as shown by quantitative immunofluorescence (both P < 0.001, n = 9). Dexamethasone markedly inhibited LPS-stimulated accumulation of mRNA for ELAM-1 and expression of ELAM-1 and ICAM-1 (IC50 < 10 nM, both P < 0.001, n = 4-9); inhibition of expression by dexamethasone was reversed by RU-486 (both P < 0.005, n = 4-6). As in the adhesion studies, cortisol but not tetrahydrocortisol inhibited expression of ELAM-1 and ICAM-1 (both P < 0.005, n = 3 or 4). In contrast, sodium salicylate (1 mM) inhibited neither adhesion nor expression of these adhesion molecules. These studies suggest that antagonism by dexamethasone of endotoxin-induced inflammation is a specific instance of the general biological principle that the glucocorticoid receptor is a hormone-dependent regulator of transcription.
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PMID:A mechanism for the antiinflammatory effects of corticosteroids: the glucocorticoid receptor regulates leukocyte adhesion to endothelial cells and expression of endothelial-leukocyte adhesion molecule 1 and intercellular adhesion molecule 1. 127 85


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