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

From Mycobacterium tuberculosis, a serologically specific polysaccharide was purified. It contained mannose, arabinose, and a trace of glucose. It was not active in hemagglutination (HA) reaction. Partial acylation of the polysaccharide was carried out with palmitoylchloride, and the synthetic lipopolysaccharide contained 15.1 per cent of esterified palmitic acid. The synthetic lipopolysaccharide had hemagglutination activity and 0.5 microg was able to sensitize 1 ml of 2 per cent erythrocyte suspension; it had the same activity as the natural antigenic lipopolysaccharide. The same antibody in the antiserum was involved in the hemagglutination reaction with both the synthetic and natural lipopolysaccharides. The sensitizing activity of the synthetic lipopolysaccharide was completely neutralized by cholesterol. Model experiments showed that the lipid moiety of hemagglutination antigen was essential for the sensitization of erythrocytes. The mechanism of the hemagglutination reaction is discussed.
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PMID:A SYNTHETIC ACYL POLYSACCHARIDE AND THE HEMAGGLUTINATION ACTIVITY. 1417 89

A comparative study of the lipopolysaccharides (LPS) isolated from Sinorhizobium meliloti SKHM 1-188 and two its LPS-mutants (Th29 and Ts22) with sharply decreased nodulation competitiveness was conducted. Polyacrylamide gel electrophoresis with sodium dodecyl sulfate revealed two forms of LPS in all the three strains: a higher molecular-weight LPS1, containing O-polysaccharide (O-PS), and a and lower molecular-weight LPS2 without O-PS. However, the LPS1 content in mutants was significantly smaller than in the parent strain. The LPS of the strains studied contained glucose, galactose, mannose, xylose, three nonidentified sugars--X1 (TGlc 0.53), X2 (TGlc 0.47), and X3 (TGlc 0.43), glucosamine, and ethanolamine, while the LPS of S. meliloti SKHM1-188 additionally contained galactosamine, glucuronic and galacturonic acids, and 2-keto-3-deoxyoctulosonic acid (KDO), as well as fatty acids, such as 3-OH C14:0, 3-OH C15:0, 3-OH C16:0, 3-OH C18:0, nonidentified hydroxy X (T3-OH C14:0 1.33), C18:0, and unsaturated C18:1 fatty acids. The LPS of both mutants were similar in the component composition but differed from the LPS of the parent strain by a lower X2, X3, and 3-OH C 14:0 content and a higher KDO, C18:0, and hydroxy X content. The LPS of all the strains were subjected to mild hydrolysis with 1% acetic acid and fractionated on a column with Sephadex G-25. The higher molecular weight fractions (2500-4000 Da) contained a set of sugars typical of intact LPS and, supposedly, corresponded to the LPS polysaccharide portion (PS1). In the lower molecular weight fractions (600-770 Da, PS2), glucose and uronic acids were the major components; galactose, mannose, and X1 were present in smaller amounts. The PS1/PS2 ratio for the two mutants was significantly lower than for strain SKHM1-188. The data obtained show that the amount of O-PS-containing molecules (LPS1) in the heterogeneous lipopolysaccharide complex of the mutants was smaller than in the SKHM1-188 LPS; this increases the hydrophobicity of the cell surface of the mutant bacteria. This supposedly contributes to their nonspecific adhesion on the roots of the host plant, thus decreasing their nodulation competitiveness.
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PMID:[Investigation of lipopolysaccharides from Sinorhizobium meliloti SKHM1-188 and two of its mutants with decreased nodulation competitiveness]. 1531 28

Inducible membrane remodeling is an adaptive mechanism that enables Gram-negative bacteria to resist killing by cationic antimicrobial peptides and to avoid eliciting an immune response. Addition of 4-amino-4-deoxy-l -arabinose (4-aminoarabinose) moieties to the phosphate residues of the lipid A portion of the lipopolysaccharide decreases the net negative charge of the bacterial membrane resulting in protection from the cationic antimicrobial peptide polymyxin B. In Salmonella enterica serovar Typhimurium, the PmrA/PmrB two-component regulatory system governs resistance to polymyxin B by controlling transcription of the 4-aminoarabinose biosynthetic genes. Transcription of PmrA-activated genes is induced by Fe(3+), which is sensed by PmrA cognate sensor PmrB, and by low Mg(2+), in a mechanism that requires not only the PmrA and PmrB proteins but also the Mg(2+)-responding PhoP/PhoQ system and the PhoP-activated PmrD protein, a post-translational activator of the PmrA protein. Surprisingly, Yersinia pestis can promote PhoP-dependent modification of its lipid A with 4-aminoarabinose despite lacking a PmrD protein. Here we report that Yersinia uses different promoters to transcribe the 4-aminoarabinose biosynthetic genes pbgP and ugd depending on the inducing signal. This is accomplished by the presence of distinct binding sites for the PmrA and PhoP proteins in the promoters of the pbgP and ugd genes. Our results demonstrate that closely related bacterial species may use disparate regulatory pathways to control genes encoding conserved proteins.
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PMID:Transcriptional regulation of the 4-amino-4-deoxy-L-arabinose biosynthetic genes in Yersinia pestis. 1571 Jun 15

Modification of the lipid A moiety of lipopolysaccharide by the addition of the sugar 4-amino-4-deoxy-L-arabinose (L-Ara4N) is a strategy adopted by pathogenic Gram-negative bacteria to evade cationic antimicrobial peptides produced by the innate immune system. L-Ara4N biosynthesis is therefore a potential anti-infective target, because inhibiting its synthesis would render certain pathogens more sensitive to the immune system. The bifunctional enzyme ArnA, which is required for L-Ara4N biosynthesis, catalyzes the NAD(+)-dependent oxidative decarboxylation of UDP-glucuronic acid to generate a UDP-4'-keto-pentose sugar and also catalyzes transfer of a formyl group from N-10-formyltetrahydrofolate to the 4'-amine of UDP-L-Ara4N. We now report the crystal structure of the N-terminal formyltransferase domain in a complex with uridine monophosphate and N-5-formyltetrahydrofolate. Using this structure, we identify the active site of formyltransfer in ArnA, including the key catalytic residues Asn(102), His(104), and Asp(140). Additionally, we have shown that residues Ser(433) and Glu(434) of the decarboxylase domain are required for the oxidative decarboxylation of UDP-GlcUA. An E434Q mutant is inactive, suggesting that chemical rather than steric properties of this residue are crucial in the decarboxylation reaction. Our data suggest that the decarboxylase domain catalyzes both hydride abstraction (oxidation) from the C-4' position and the subsequent decarboxylation.
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PMID:Structure and function of both domains of ArnA, a dual function decarboxylase and a formyltransferase, involved in 4-amino-4-deoxy-L-arabinose biosynthesis. 1580 94

The lipopolysaccharide from the freshwater bacterium Rahnella aquatilis 1-95 has been isolated and investigated for the first time. The structural components of the lipopolysaccharide molecule: lipid A, core oligosaccharide, and O-specific polysaccharide were isolated by mild acidic hydrolysis. In lipid A, 3-hydroxytetradecanoic and tetradecanoic acids were found to be the predominant fatty acids. In the core oligosaccharide, galactose, arabinose, fucose, and an unidentified component were shown to be the major monosaccharides. The O-specific polysaccharide consists of a regularly repeating trisaccharide unit with the acyl and phosphate following structure: [structure: see text] groups have been shown to be responsible for the toxic and pyrogenic properties of the lipopolysaccharide of R. aquatilis.
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PMID:[Characterization of the lipopolysaccharide from Rahnella aquatilis 1-95]. 1621 49

Results of studies of the structurally unique O-chains of lipopolysaccharides, which were isolated from the dry biomass of Pseudomonas fluorescens IMB 2108 (biovar II) and IMB 2111 (biovar IV) by the Westphal technique and purified by repeated ultracentrifugation, are reported. The bulk of the lipopolysaccharide preparations contained S- and R-molecules at an average molar ratio of 1: 2. The main components of the hydrophobic moiety of lipid A were 3-hydroxydecanoic, 2-hydroxydodecanoic, 3-hydroxydodecanoic, dodecanoic, hexadecanoic, and octadecanoic acids, as well as hexadecenoic and octadecenoic acids. Glucosamine and phosphoethanolamine were identified as components of the hydrophilic moiety of lipid A. The degree of lipid A phosphorylation amounted to 3-4%. Fractions of the core oligosaccharide contained glucose, galactose, mannose, rhamnose, arabinose, glucosamine (only in strain IMB 2108), alanine, phosphoethanolamine, phosphorus, and 2-keto-3-deoxyoctulosonic acid (KDO). Heptose was present in trace amounts. O-specific polysaccharide chains were represented by a linear polymer of D-glucose units, which were linked together via alpha-(1,4) glycoside bonds. The existence of P. fluorescens strains that have alpha-1,4-glucan as the O-chain of their lipopolysaccharides has not been described before.
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PMID:[Characterization of lipopolysaccharides from Pseudomonas fluorescens IMB 2108 (biovar II) and IMB 2111 (biovar IV) with O-chains represented by alpha-glucan]. 1631 82

The carbohydrates present in lipopolysaccharide (LPS) from Pseudomonas solanacearum are rhamnose, xylose, 2-amino-2-deoxyglucose, glucose, heptose, and 2-keto-3-deoxyoctonate. LPS extracted from cultures grown on either glycerol or glucose (as the major source of carbon) and extracted after various incubation periods had similar compositions. The LPS from several strains of the bacterium contained the same component sugars, but the amounts of each sugar varied considerably. It was observed, however, that xylose and 2-amino-2-deoxyglucose increased proportionately with rhamnose, the major component. Phenol-water-extracted LPS contained measurable amounts of nucleic acid, protein, and arabinan, but none of these polymers were detected in LPS extracted with phenol-chloroform-petroleum ether. Polysaccharides liberated from LPS by mild acid hydrolysis were purified by gel filtration. Carbohydrate analysis of the LPS from a virulent, fluidal strain (K60) showed that the O-specific antigen consisted of rhamnose, xylose, and 2-amino-2-deoxyglucose in the proportions 4:1:1. The LPS of an avirulent, afluidal strain (B1) lacked the O-specific antigen; the R-core region consisted of rhamnose, glucose, heptose, and 2-keto-3-deoxyoctonate. Methylation analysis indicated that the K60 O-specific antigen was composed of a hexasaccharide repeating unit containing 3-, 2-, and 3,4-substituted rhamnopyranosyl residues, 3-substituted 2-amino-2-deoxyglucose, and terminal xylopyranose in the molar ratios 2:1:1:1:1.
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PMID:Chemical Characterization of the Lipopolysaccharide of Pseudomonas solanacearum. 1634 38

The nutritional and physiological characteristics of 15 isolates from four species of the Azolla fern were determined. Although some minor variation existed in levels of urease activity, ability to utilize xylose, and formation of N(2) gas from NO(3), all 15 isolates were rather similar and believed to represent a single species. These eubacteria exhibited aminopeptidase activity and became viscous when treated with KOH, similar to gram-negative organisms; however, the absence of lipopolysaccharide and 2-keto-3-deoxyoctonate in cell walls indicated that they are truly gram-positive organisms. They are unusual because peptidoglycan could not be detected during most of their growth cycle. The presence of lysine as the major diamino acid in cell wall hydrolysates, the inability to hydrolyze cellulose, and the distinctive developmental pattern with rods and "V" forms present during log phase, becoming progressively shorter until cocci dominated during stationary and death phases, indicated that these organisms belong to the genus Arthrobacter Conn and Dimmick. With the exception of the inability to hydrolyze gelatin, their characteristics are consistent with those of the type species, Arthrobacter globiformis Conn and Dimmick.
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PMID:Identification of eubacteria isolated from leaf cavities of four species of the N-fixing azolla fern as arthrobacter conn and dimmick. 1634 44

Plasmids in Rhizobium spp. are relatively large, numerous, and difficult to cure. Except for the symbiotic plasmid, little is known about their functions. The primary objective of our investigation was to obtain plasmid-cured derivatives of Rhizobium leguminosarum bv. trifolii by using a direct selection system and to determine changes in the phenotype of the cured strains. Three strains of rhizobia were utilized that contained three, four, and five plasmids. Phenotypic effects observed after curing of plasmids indicated that the plasmids were involved in the utilization of adonitol, arabinose, catechol, glycerol, inositol, lactose, malate, rhamnose, and sorbitol and also influenced motility, lipopolysaccharide production, and utilization of nitrate. Specific staining of 26 enzymes electrophoretically separated on starch gels indicated that superoxide dismutase, hexokinase, and carbamate kinase activities were affected by curing of plasmids. Curing of cryptic plasmids also influenced nodulation and growth of plants on nitrogen-deficient media. The alteration in the ability to utilize various substrates after curing of plasmids suggests that the plasmids may encode genes that contribute significantly to the saprophytic competence of rhizobia in soil.
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PMID:Utilization of carbon substrates, electrophoretic enzyme patterns, and symbiotic performance of plasmid-cured clover rhizobia. 1634 39

The phenotypic, molecular, and virulence properties of 46 Vibrio anguillarum-related (VAR) strains isolated from diseased fish and shellfish and from the environment were investigated. Twelve reference strains belonging to the 10 serotypes of V. anguillarum and the Vibrio splendidus type strain were included for comparison. Numerical taxonomy studies allowed us to group the isolates into four phena. The main phenotypic traits to differentiate VAR strains from V. anguillarum were fermentation of arabinose and mannitol, indole and Voges-Proskauer reactions, gelatin and casein hydrolysis, hemolytic activity, growth at 37 and 4 degrees C, and resistance to ampicillin. Serological analysis confirmed that phena I and II were composed mainly of strains of V. anguillarum, while phena III and IV included VAR strains. Excluding the reference strains, the typeable isolates belonged to serotypes O3 (15 strains), O4 (3 strains), and O5 (2 strains) of V. anguillarum. The infectivity trials showed that only 9 of a total of 24 strains tested displayed virulence for rainbow trout. Virulent strains (50% lethal dose ranging from 10 to 10 cells) included V. anguillarum strains belonging to serotypes O1 (one strain), O2 (one strain), O3 (three isolates), and O4 (one isolate) and only three strains of the VAR group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of lipopolysaccharide and outer membrane proteins showed heterogeneity not only among the 10 V. anguillarum serotypes but also within the VAR group. Immunoblot assays demonstrated a close relationship among V. anguillarum strains from the same serotype, while strains from different serotypes were not antigenically related. The VAR strains did not share antigenic components with the serotypes of V. anguillarum tested (serotypes O1 to O5). Plasmids were detected in only 19 of the total of 59 strains. The majority of the strains carrying plasmids were grouped within phenon IV, in which plasmid bands of 27 and 36 MDa were found in all the isolates. No correlation between the plasmid content of VAR microorganisms and their phenotypic or virulence characteristics was observed. From these results it can be concluded that VAR strains associated with disease should be included together with V. anguillarum in the formulation of vaccines against vibriosis.
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PMID:Phenotypic Characteristics and Virulence of Vibrio anguillarum-Related Organisms. 1634 42


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