Chemotypes of Veillonella lipopolysaccharides

Lipopolysaccharides (LPS) were isolated by phenol-water extraction from 34 strains of Veillonella, and examined by paper chromatography and colorimetric methods for the presence of neutral sugars, amino sugars and 2-keto-3-deoxy-octonate (KDO). Several preparations were also examined for neutral sugars by gas liquid chromatography. The LPS had in common glucosamine, galactosamine, L-glycero-D-manno-heptose glucose and KDO. Most LPS contained galactose, and a few rhamnose. D-glycero-D-manno-heptose was found in LPS from one of the strains. Based on the sugar composition of the LPS, the Veillonella strains could be classified into four chemotypes.     

Structure of bacterial lipopolysaccharides

Bacterial lipopolysaccharides are the major components of the outer surface of Gram-negative bacteria They are often of interest in medicine for their immunomodulatory properties. In small amounts they can be beneficial, but in larger amounts they may cause endotoxic shock. Although they share a common architecture, their structural details exert a strong influence on their activity. These molecules comprise: a lipid moiety, called lipid A, which is considered to be the endotoxic component, a glycosidic part consisting of a core of approximately 10 monosaccharides and, in "smooth-type" lipopolysaccharides, a third region, named O-chain, consisting of repetitive subunits of one to eight monosaccharides responsible for much of the immunospecificity of the bacterial cell.     

Chemotypes of Fusobacterium nucleatum lipopolysaccharides

Lipopolysaccharides (LPS) were isolated from 20 strains of Fusobacterium nucleatum and examined by paper chromatography, gas liquid chromatography and colorimetric methods for the presence of neutral sugars, amino sugars and 2-keto-3-dexoxy-octonate (KDO). The LPS had in common glucosamine, L-glycero-D-manno-heptose, glucose and KDO. The KDO content was low. Galatose, rhamnose and D-glycero-D-manno-heptose were found in some strains. Based on the sugar composition of the LPS, the F. nucleatum strains could be classified into six chemotypes.     

Structure and function of lipopolysaccharides

The lipopolysaccharides of Gram-negative bacteria have a profound effect on the mammalian immune system and are of great significance in the pathophysiology of many disease processes. Consideration is given in this review to the relationship between structure and function of these lipopolysaccharides.     

Composition of lipopolysaccharides fromRhizobium andAgrobacterium

Lipopolysaccharides were prepared from 9Agrobacterium and 16Rhizobium strains. Glucose and rhamnose were the only monosaccharides present in all preparations, but mannose, glucosamine and 4-O-methylglucuronic acid were common components. Fucose (present in 9 strains), galactose (10 strains), xylose (3 strains) and arabinose (1 strain) were also detected but there was no evidence of dideoxy sugars, of heptose, or of other hexosamines. The possible significance of the results in the serological classification ofRhizobium andAgrobacterium, and in host selection ofRhizobium is discussed.     

Chemical analysis of Azospirillum lipopolysaccharides

Lipopolysaccharides (LPS) were extracted by hot phenol-water from five strains each of Azospirillum lipoferum and Azospirillum brasilense. Rhamnose, glucose, glucosamine and 3-deoxy-d-mannooctulosonic acid were comon sugar constituents of all LPS preparations. 2-O-Mefucose, 3-O-Me-fucose, 3-O-Me-rhamnose and 2-O-Megalactose were found in LPSs of some A. brasilense strains. Fatty acid spectra from all LPSs studied were almost identical with predominance of 3-hydroxymyristic and 3-hydroxypalmitic acids. 3-Hydroxypalmitic acid was the only amide-linked fatty acid. Lipopolysaccharides isolated from A. brasilense showed higher heterogeneity in sugar composition than those from A. lipoferum.Abbreviations glc gas liquid chromatography - ms mass spectrometry - LPS lipopolysaccharide - dOclA 3-deoxy-d-mannooctulosonic acid - 3-OH-16:0 3-hydroxypalmitic acid - nir^- nitrite reductase negative - nir⁺ nitrite reductase positive     

Heterogeneity of Rhizobium lipopolysaccharides.

The lipopolysaccharides ( LPSs ) from strains of Rhizobium leguminosarum, Rhizobium trifolii, and Rhizobium phaseoli were isolated and partially characterized by mild acid hydrolysis and by polyacrylamide gel electrophoresis. Mild acid hydrolysis results in a precipitate which can be removed by centrifugation or extraction with chloroform. The supernatant contains polysaccharides which, in general, are separated into two fractions ( LPS1 and LPS2 ) by Sephadex G-50 gel filtration chromatography. The higher-molecular-weight LPS1 fractions among the various Rhizobium strains are highly variable in composition and reflect the variability reported in the intact LPSs (R. W. Carlson and R. Lee, Plant Physiol. 71:223-228, 1983; Carlson et al., Plant Physiol. 62:912-917, 1978; Zevenhuizen et al., Arch. Microbiol. 125:1-8, 1980). The LPS1 fraction of R. leguminosarum 128C53 has a higher molecular weight than all other LPS1 fractions examined. All LPS2 fractions examined are oligosaccharides with a molecular weight of ca. 600. The major sugar component of all LPS2 oligosaccharides is uronic acid. The LPS2 compositions are similar for strains of R. leguminosarum and R. trifolii, but the LPS2 from R. phaseoli was different in that it contained glucose, a sugar not found in the other LPS2 fractions or found only in trace amounts. Polyacrylamide gel electrophoretic analysis shows that each LPS contains two banding regions, a higher-molecular-weight heterogeneous region often containing many bands and a lower-molecular-weight band. The lower-molecular-weight bands of all LPSs have the same electrophoretic mobility, which is greater than that of lysozyme. The banding pattern of the heterogeneous regions varies among the different Rhizobium strains. In the case of R. leguminosarum 128C53 LPS, the heterogeneous region of a higher molecular weight than is this region from all other Rhizobium strains examined and consists of many bands separated from one another by a small and apparently constant molecular weight interval. When the heterogeneous region of R. Leguminosarum 128C53 LPS was cut from the gel and analyzed, its composition was found to be that of the intact LPS, whereas the lower-molecular-weight band contains only sugars found in the LPS2 oligosaccharide. In the case of R. leguminosarum 128C63 and R. trifolii 0403 LPSs, the heterogeneous regions are similar and consist of several band s separated by a large-molecular-weight interval with a the major band of these heterogeneous regions having the lowest molecular weight with an electrophoretic mobility near that of beta-lactoglobulin. The heterogeneous region from R. phaseoli 127K14 consists of several bands with electrophoretic mobilities near that of beta-lactoglobulin, whereas this region from R. trifolii 162S7 shows a continuous staining region, indicating a great deal of heterogeneity. The results described in this paper are discussed with regard to the reported properties of Escherichia coli and Salmonella LPSs.     

Chylomicrons promote intestinal absorption of lipopolysaccharides

Recent data suggest that dietary fat promotes intestinal absorption of lipopolysaccharides (LPS) from the gut microflora, which might contribute to various inflammatory disorders. The mechanism of fat-induced LPS absorption is unclear, however. Intestinal-epithelial cells can internalize LPS from the apical surface and transport LPS to the Golgi. The Golgi complex also contains newly formed chylomicrons, the lipoproteins that transport dietary long-chain fat through mesenteric lymph and blood. Because LPS has affinity for chylomicrons, we hypothesized that chylomicron formation promotes LPS absorption. In agreement with our hypothesis, we found that CaCo-2 cells released more cell-associated LPS after incubation with oleic-acid (OA), a long-chain fatty acid that induces chylomicron formation, than with butyric acid (BA), a short-chain fatty acid that does not induce chylomicron formation. Moreover, the effect of OA was blocked by the inhibitor of chylomicron formation, Pluronic L-81. We also observed that intragastric triolein (TO) gavage was followed by increased plasma LPS, whereas gavage with tributyrin (TB), or TO plus Pluronic L-81, was not. Most intestinally absorbed LPS was present on chylomicron remnants (CM-R) in the blood. Chylomicron formation also promoted transport of LPS through mesenteric lymph nodes (MLN) and the production of TNFalpha mRNA in the MLN. Together, our data suggest that intestinal epithelial cells may release LPS on chylomicrons from cell-associated pools. Chylomicron-associated LPS may contribute to postprandial inflammatory responses or chronic diet-induced inflammation in chylomicron target tissues.     

Cell surface lipopolysaccharides of different rhizobia

Abstract Lime was added to a forest acid soil rich in organic matter. During five weeks of initial incubation at room temperature (until the various limed soil samples reached stabilized pHs of 5.5, 6.0 or 6.5), there were rapid increases in the bacterial population, denitrifiers, and fungal mycelia, particularly in the heaviest limed sample. Conversely, nitrite oxidizers decreased to undetectable numbers regardless of the lime dose applied. At this time soil samples were amended with 5% of fresh soil. During 12 weeks of subsequent incubation at 28°C, the bacterial population was favoured by increasing soil pH; nevertheless, at the end of the incubation the positive effect was only significant at pH 6.0 and 6.5. By contrast fungi were depressed by raising the pH. Nitrifiers and denitrifiers were more numerous in the limed than in the unlimed soils but only in samples at pH 6.5 were the differences significant throughout the incubation period.     

SDS-polyacrylamide gel electrophoresis of lipopolysaccharides.

Lipopolysaccharides (LPS) prepared from four different species of Neisseria have been separated by SDS-polyacrylamide gel electrophoresis. Each LPS possessed a characteristic mobility on gels. Examination of the effect of acrylamide concentration on migration illustrated that the basis of the separation was molecular size and not intrinsic charge.     

Homogeneity of lipopolysaccharides from Acholeplasma.

Five methods were employed to determine the heterogeneity or homogeneity of lipopolysaccharides from four acholeplasmal species, Acholeplasma axanthum, A. granularum, A. laidlawii, and A. modicum. A axanthum lipopolysaccharide behaved as a single component in all tests. A. granularum exhibited two components of identical composition and antigenic specificity. A. modicum lipopolysaccharide behaved as three components in two tests, but all three were similar in composition and identical serologically. The separable components of lipopolysaccharides from A. granularum and A. modicum probably represent size differences only. A. laidlwii lipopolysaccharide contained two distinct components by all methods. One was identified as the previously reported amino sugar polymer, whereas the other was a lipopolysaccharide containing both neutral and amino sugars.     

Interaction of antimicrobial peptides with lipopolysaccharides

We study the interaction of antimicrobial peptides with lipopolysaccharide (LPS) bilayers to understand how antimicrobial peptides interact with the LPS monolayer on the outer membrane of Gram-negative bacteria. LPS in water spontaneously forms a multilamellar structure composed of symmetric bilayers. We performed X-ray lamellar diffraction and wide-angle in-plane scattering to study the physical characteristics of LPS multilayers. The multilayer alignment of LPS is comparable to phospholipids. Thus, it is suitable for the application of oriented circular dichroism (OCD) to study the state of peptides in LPS bilayers. At high hydration levels, the chain melting temperature in multilamella detected by X-ray diffraction is the same as that of LPS aqueous dispersions, as measured by calorimetry. LPS has a strong CD, but with a careful subtraction of the lipid background, the OCD of peptides in LPS is measurable. The method was tested successfully with melittin. It was then applied to two representative antimicrobial peptides, magainin and protegrin. At peptide concentrations comparable to the physiological conditions, both peptides penetrate transmembrane in LPS bilayers. The results imply that antimicrobial peptides readily penetrate the LPS monolayer of the outer membrane.     

The R-type lipopolysaccharides of Neisseria meningitidis

The lipopolysaccharides of all the different serogroups of Neisseria meningitidis are of the "R" type despite the morphologically smooth appearance and the demonstrated virulence of the organisms from which they were derived. This was confirmed when each of the lipopolysaccharides was found to be devoid of detectable O-antigen side chains, giving only a low "molecular" weight core oligosaccharide when subjected to mild acid hydrolysis. The cores were modified by dephosphorylation and subjected to sugar and methylation analysis by gas-liquid chromatography. Although all the different cores contained identical components (glucose, galactose, glucosamine, heptose, and 2-keto-3-deoxyoctonate) they could be separated into three distinct categories according to their galactose:glucose ratios. These categories are typified by the cores obtained from groups A, C, and 29-e which have galactose:glucose ratios of 1:2, 2:2, and 2:1, respectively. The modified cores were methylated and analyzed by gas chromatography--mass spectrometry and on the basis of differences in the derived methylated sugars the cores could again be divided into the same three categories as above. This structural diversity also results in some serological specificity as demonstrated by the complete serogroup specificity of the group A lipopolysaccharide.