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

Aiming at improving classification and taxonomy of Gram-negative phytopathogenic bacteria, we studied the structure of the lipopolysaccharide of Ralstonia solanacearum. Mild acid hydrolysis of the lipopolysaccharide of strain Toudk-2 followed by gel chromatography resulted in an O-polysaccharide and two oligosaccharide fractions. The smallest-size oligosaccharide fraction was studied by sugar analysis, high-resolution electrospray ionization mass spectrometry, and, after fractionation by anion-exchange chromatography on HiTrap Q, by one- and two-dimensional (1)H and (13)C NMR spectroscopy. It was found that the isolated oligosaccharides consist of the lipopolysaccharide core with one O-polysaccharide repeat (O-unit) attached. The core exists in two major glycoforms differing from each other in a lateral octulosonic acid residue, which is either D-glycero-D-talo-oct-2-ulosonic acid or 3-deoxy-D-manno-oct-2-ulosonic acid. A peculiar feature of the core is the occurrence of 4-amino-4-deoxy-L-arabinose nonstoichiometrically linked to a heptose residue. The full structures of the core and the biological O-unit as well as the site of the attachment of the O-unit to the core were established.
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PMID:Structure of the oligosaccharide chain of the SR-type lipopolysaccharide of Ralstonia solanacearum Toudk-2. 1861 25

The water-soluble polysaccharide (CPP), with a molecular mass of 1.1x10(4) Da, was obtained from the roots of Codonopsis pilosula. Structure feature investigation by a combination of chemical and instrumental analysis revealed that CPP had a backbone consisting of (1-->3)-linked-beta-D-galactopyranosyl, (1-->2, 3)-linked-beta-D-galactopyranosyl and (1-->3)-linked-alpha-D-rhamnopyranosyl residues, which were branched with two glycosyl residues composed of alpha-L-arabinose-(1-->5)-alpha-L-arabinose(1-->linked residues at the O-2 position of galactosyl along the main chain in the ratio of 1:1:2:1:1. Preliminary immunological tests in vitro showed CPP could stimulate concanavalin A (ConA)- or lipopolysaccharide (LPS)-induced lymphocyte proliferation in a dose-dependent manner.
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PMID:Structural characterization of a water-soluble polysaccharide from the roots of Codonopsis pilosula and its immunity activity. 1864 Jan 51

The lipopolysaccharide (LPS) from a new Enterobacteriaceae species, Rahnella aquatilis 2-95, was isolated and investigated. The structural components of the LPS molecule, namely, lipid A, core oligosaccharide, and O-specific polysaccharide, were obtained by mild acid hydrolysis. In lipid A, 3-oxytetradecanoic and tetradecanoic acids were found to be the predominant fatty acids. The major monosaccharides of the core oligosaccharide were galactose, arabinose, fucose, rhamnose, and an unidentified component. The O-specific polysaccharide was found to be assembled of a repeated trisaccharide unit of the following structure: [structure: see text]. The R. aquatilis 2-95 LPS is less toxic and more pyrogenic as compared to the one from the R. aquatilis 1-95 strain studied earlier. Both acyl and phosphate groups are essential for toxic and pyrogenic activity of R. aquatilis 2-95 LPS.
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PMID:[Chemical characteristics and endotoxic activity of the lipopolysaccharide of Rahnella aquatilis 2-95]. 1868 51

Recombinant bacterial vaccines must be fully attenuated for animal or human hosts to avoid inducing disease symptoms while exhibiting a high degree of immunogenicity. Unfortunately, many well-studied means for attenuating Salmonella render strains more susceptible to host defense stresses encountered following oral vaccination than wild-type virulent strains and/or impair their ability to effectively colonize the gut-associated and internal lymphoid tissues. This thus impairs the ability of recombinant vaccines to serve as factories to produce recombinant antigens to induce the desired protective immunity. To address these problems, we designed strains that display features of wild-type virulent strains of Salmonella at the time of immunization to enable strains first to effectively colonize lymphoid tissues and then to exhibit a regulated delayed attenuation in vivo to preclude inducing disease symptoms. We recently described one means to achieve this based on a reversible smooth-rough synthesis of lipopolysaccharide O antigen. We report here a second means to achieve regulated delayed attenuation in vivo that is based on the substitution of a tightly regulated araC P(BAD) cassette for the promoters of the fur, crp, phoPQ, and rpoS genes such that expression of these genes is dependent on arabinose provided during growth. Thus, following colonization of lymphoid tissues, the Fur, Crp, PhoPQ, and/or RpoS proteins cease to be synthesized due to the absence of arabinose such that attenuation is gradually manifest in vivo to preclude induction of diseases symptoms. Means for achieving regulated delayed attenuation can be combined with other mutations, which together may yield safe efficacious recombinant attenuated Salmonella vaccines.
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PMID:Salmonella enterica serovar typhimurium strains with regulated delayed attenuation in vivo. 1910 74

Structure components (lipid A. oligosaccharide core, and O-specific polysaccharide) of the lipopolysaccharide from 8 strains of Pragia fontium were obtained as a result of mild acidic hydrolysis. The macromolecular organization of lipopolysaccharides of studied strains was heterogeneous and presented both by S-forms, and R- or SR-forms. It was established that as to fatty acid composition lipids A of tested strains were represented by one chemotype with predominant 3-hydroxytetradecanoic fatty acid. An analysis ofmonosaccharide composition of core oligosaccharides has detected 5 chemotypes, and glucose, galactose, rhamnose, ribose, arabinose, xylose and mannose were identified in them. It was shown that O-specific polysaccharides consisted of glucose, galactose, rhamnose, and mannose that demonstrated their belonging to 4 chemotypes.
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PMID:[Chemical characteristic of structure components of Pragia fontium lipopolysaccharides]. 1914 Apr 16

To elucidate the minimal lipopolysaccharide (LPS) structure needed for the viability of Escherichia coli, suppressor-free strains lacking either the 3-deoxy-d-manno-oct-2-ulosonic acid transferase waaA gene or derivatives of the heptosyltransferase I waaC deletion with lack of one or all late acyltransferases (lpxL/M/P) and/or various outer membrane biogenesis factors were constructed. Delta(waaC lpxL lpxM lpxP) and waaA mutants exhibited highly attenuated growth, whereas simultaneous deletion of waaC and surA was lethal. Analyses of LPS of suppressor-free waaA mutants grown at 21 degrees C, besides showing accumulation of free lipid IV(A) precursor, also revealed the presence of its pentaacylated and hexaacylated derivatives, indicating in vivo late acylation can occur without Kdo. In contrast, LPS of Delta(waaC lpxL lpxM lpxP) strains showed primarily Kdo(2)-lipid IV(A), indicating that these minimal LPS structures are sufficient to support growth of E. coli under slow-growth conditions at 21/23 degrees C. These lipid IV(A) derivatives could be modified biosynthetically by phosphoethanolamine, but not by 4-amino-4-deoxy-l-arabinose, indicating export defects of such minimal LPS. DeltawaaA and Delta(waaC lpxL lpxM lpxP) exhibited cell-division defects with a decrease in the levels of FtsZ and OMP-folding factor PpiD. These mutations led to strong constitutive additive induction of envelope responsive CpxR/A and sigma(E) signal transduction pathways. Delta(lpxL lpxM lpxP) mutant, with intact waaC, synthesized tetraacylated lipid A and constitutively incorporated a third Kdo in growth medium inducing synthesis of P-EtN and l-Ara4N. Overexpression of msbA restored growth of Delta(lpxL lpxM lpxP) under fast-growing conditions, but only partially that of the Delta(waaC lpxL lpxM lpxP) mutant. This suppression could be alleviated by overexpression of certain mutant msbA alleles or the single-copy chromosomal MsbA-498V variant in the vicinity of Walker-box II.
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PMID:Escherichia coli K-12 Suppressor-free Mutants Lacking Early Glycosyltransferases and Late Acyltransferases: minimal lipopolysaccharide structure and induction of envelope stress response. 1934 44

Burkholderia cenocepacia is an opportunistic pathogen that displays a remarkably high resistance to antimicrobial peptides. We hypothesize that high resistance to antimicrobial peptides in these bacteria is because of the barrier properties of the outer membrane. Here we report the identification of genes for the biosynthesis of the core oligosaccharide (OS) moiety of the B. cenocepacia lipopolysaccharide. We constructed a panel of isogenic mutants with truncated core OS that facilitated functional gene assignments and the elucidation of the core OS structure in the prototypic strain K56-2. The core OS structure consists of three heptoses in the inner core region, 3-deoxy-d-manno-octulosonic acid, d-glycero-d-talo-octulosonic acid, and 4-amino-4-deoxy-l-arabinose linked to d-glycero-d-talo-octulosonic acid. Also, glucose is linked to heptose I, whereas heptose II carries a second glucose and a terminal heptose, which is the site of attachment of the O antigen. We established that the level of core truncation in the mutants was proportional to their increased in vitro sensitivity to polymyxin B (PmB). Binding assays using fluorescent 5-dimethylaminonaphthalene-1-sulfonyl-labeled PmB demonstrated a correlation between sensitivity and increased binding of PmB to intact cells. Also, the mutant producing a heptoseless core OS did not survive in macrophages as compared with the parental K56-2 strain. Together, our results demonstrate that a complete core OS is required for full PmB resistance in B. cenocepacia and that resistance is due, at least in part, to the ability of B. cenocepacia to prevent binding of the peptide to the bacterial cell envelope.
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PMID:Biosynthesis and structure of the Burkholderia cenocepacia K56-2 lipopolysaccharide core oligosaccharide: truncation of the core oligosaccharide leads to increased binding and sensitivity to polymyxin B. 1952 27

The lipopolysaccharide O antigen of Shigella flexneri 2a has two preferred chain lengths, a short (S-OAg) composed of an average of 17 repeated units and a very long (VL-OAg) of about 90 repeated units. These chain length distributions are controlled by the chromosomally encoded WzzB and the plasmid-encoded Wzz(pHS-2) proteins, respectively. In this study, genes wzzB, wzz(pHS-2) and wzy (encoding the O-antigen polymerase) were cloned under the control of arabinose- and rhamnose-inducible promoters to investigate the effect of varying their relative expression levels on O antigen polysaccharide chain length distribution. Controlled expression of the chain length regulators wzzB and wzz(pHS-2) revealed a dose-dependent production of each modal length. Increase in one mode resulted in a parallel decrease in the other, indicating that chain length regulators compete to control the degree of O antigen polymerization. Also, when expression of the wzy gene is low, S-OAg but not VL-OAg is produced. Production of VL-OAg requires high induction levels of wzy. Thus, the level of expression of wzy is critical in determining O antigen modal distribution. Western blot analyses of membrane proteins showed comparable high levels of the WzzB and Wzz(pHS-2) proteins, but very low levels of Wzy. In vivo cross-linking experiments and immunoprecipitation of membrane proteins did not detect any direct interaction between Wzy and WzzB, suggesting the possibility that these two proteins may not interact physically but rather by other means such as via translocated O antigen precursors.
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PMID:The cellular level of O-antigen polymerase Wzy determines chain length regulation by WzzB and WzzpHS-2 in Shigella flexneri 2a. 1955 92

Burkholderia pseudomallei, the etiological agent of melioidosis, is a facultative intracellular pathogen. As B. pseudomallei is a gram-negative bacterium, its outer membrane contains lipopolysaccharide (LPS) molecules, which have been shown to have low-level immunological activities in vitro. In this study, the biological activities of B. pseudomallei LPS were compared to those of Burkholderia thailandensis LPS, and it was found that both murine and human macrophages produced levels of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-10 in response to B. pseudomallei LPS that were lower than those in response to B. thailandensis LPS in vitro. In order to elucidate the molecular mechanisms underlying the low-level immunological activities of B. pseudomallei LPS, its lipid A moiety was characterized using mass spectrometry. The major lipid A species identified in B. pseudomallei consists of a biphosphorylated disaccharide backbone, which is modified with 4-amino-4-deoxy-arabinose (Ara4N) at both phosphates and penta-acylated with fatty acids (FA) C(14:0)(3-OH), C(16:0)(3-OH), and either C(14:0) or C(14:0)(2-OH). In contrast, the major lipid A species identified in B. thailandensis was a mixture of tetra- and penta-acylated structures with differing amounts of Ara4N and FA C(14:0)(3-OH). Lipid A species acylated with FA C(14:0)(2-OH) were unique to B. pseudomallei and not found in B. thailandensis. Our data thus indicate that B. pseudomallei synthesizes lipid A species with long-chain FA C(14:0)(2-OH) and Ara4N-modified phosphate groups, allowing it to evade innate immune recognition.
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PMID:Structural and biological diversity of lipopolysaccharides from Burkholderia pseudomallei and Burkholderia thailandensis. 1969 25

RfaH is a transcriptional antiterminator that reduces the polarity of long operons encoding secreted and surface-associated cell components of Salmonella enterica serovar Typhimurium, including O antigen and lipopolysaccharide core sugars. A DeltarfaH mutant strain is attenuated in mice (50% lethal dose [LD(50)], >10(8) CFU). To examine the potential for using rfaH in conjunction with other attenuating mutations, we designed a series of strains in which we replaced the native rfaH promoter with the tightly regulated arabinose-dependent araC P(BAD) promoter so that rfaH expression was dependent on exogenously supplied arabinose provided during in vitro growth. Following colonization of host lymphoid tissues, where arabinose was not available, the P(BAD) promoter was no longer active and rfaH was not expressed. In the absence of RfaH, O antigen and core sugars were not synthesized. We constructed three mutant strains that expressed different levels of RfaH by altering the ribosome-binding sequence and start codon. One mutation, DeltaP(rfaH178), was introduced into the attenuated vaccine strain chi9241 (DeltapabA DeltapabB DeltaasdA) expressing the pneumococcal surface protein PspA from an Asd(+) balanced-lethal plasmid. Mice immunized with this strain and boosted 4 weeks later induced higher levels of serum immunoglobulin G specific for PspA and for outer membrane proteins from other enteric bacteria than either an isogenic DeltarfaH derivative or the isogenic RfaH(+) parent. Eight weeks after primary oral immunization, mice were challenged with 200 LD(50) of virulent Streptococcus pneumoniae WU2. Immunization with DeltaP(rfaH178) mutant strains led to increased levels of protection compared to that of the parent chi9241 and of a DeltarfaH derivative of chi9241.
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PMID:Regulated delayed expression of rfaH in an attenuated Salmonella enterica serovar typhimurium vaccine enhances immunogenicity of outer membrane proteins and a heterologous antigen. 1980 38


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