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PubMed2006

Kdo2-Lipid A of Escherichia coli, a defined endotoxin that activates macrophages via TLR-4.

The LIPID MAPS Consortium (www.lipidmaps.org) is developing comprehensive procedures for identifying all lipids of the macrophage, following activation by endotoxin. The goal is to quantify temporal and spatial changes in lipids that occur with cellular metabolism and to develop bioinformatic approaches that establish dynamic lipid networks. To achieve these aims, an endotoxin of the highest possible analytical specification is crucial. We now report a large-scale preparation of 3-deoxy-D-manno-octulosonic acid (Kdo)(2)-Lipid A, a nearly homogeneous Re lipopolysaccharide (LPS) sub-structure with endotoxin activity equal to LPS. Kdo(2)-Lipid A was extracted from 2 kg cell paste of a heptose-deficient Escherichia coli mutant. It was purified by chromatography on silica, DEAE-cellulose, and C18 reverse-phase resin. Structure and purity were evaluated by electrospray ionization/mass spectrometry, liquid chromatography/mass spectrometry and (1)H-NMR. Its bioactivity was compared with LPS in RAW 264.7 cells and bone marrow macrophages from wild-type and toll-like receptor 4 (TLR-4)-deficient mice. Cytokine and eicosanoid production, in conjunction with gene expression profiling, were employed as readouts. Kdo(2)-Lipid A is comparable to LPS by these criteria. Its activity is reduced by >10(3) in cells from TLR-4-deficient mice. The purity of Kdo(2)-Lipid A should facilitate structural analysis of complexes with receptors like TLR-4/MD2.

Animals↗

PubMed2000

Effects of D-mannoheptulose and its hexaacetate ester on hormonal secretion from the perfused pancreas.

D-mannoheptulose was recently proposed to be transported into cells by GLUT2, whereas its hexaacetate ester may cross the plasma membrane without requiring the intervention of a specific carrier system. In the light of these proposals, the effects of unesterified D-mannoheptulose and D-mannoheptulose hexaacetate upon hormonal secretion by the perfused rat pancreas were now investigated. Unesterified D-mannoheptulose (1.7 mM) inhibited insulin release and, in most cases, somatostatin output, whereas it augmented glucagon secretion by pancreases exposed to D-glucose (3.3 mM) in the presence of the dimethyl ester of succinic acid (SAD, 10.0 mM). The heptose failed, however, to affect hormonal secretion in the sole presence of SAD. D-mannoheptulose hexaacetate (also 1.7 mM) reproduced, within limits, the effects of unesterified D-mannoheptulose in pancreases exposed to both D-glucose and SAD. In addition, however, the ester displayed a positive effect upon the secretion of the three hormones, even in the sole presence of SAD. These findings support the view that monosaccharide esters may affect the secretion of pancreatic hormones in a dual manner, linked to both the metabolic response to their glucidic moiety and a direct effect of the ester itself. Moreover, they reveal that unesterified D-mannoheptulose is able to antagonize the effect of D-glucose upon hormonal secretion even in cells claimed not to contain GLUT2. The modality by which D-mannoheptulose apparently gains access to the cytosol of these cells remains to be elucidated.

Analysis of Variance↗

PubMed2000

D-mannoheptulose uptake and its metabolic and secretory effects in human pancreatic islets.

D-mannoheptulose was recently proposed to be transported into cells at the intervention of GLUT2. Since GLUT1, rather than GLUT2, represents the major carrier system for the transport of monosaccharides across the islet B-cell plasma membrane in human subjects, the uptake of D-mannoheptulose and its metabolic and secretory effects were investigated in human islets. The uptake of D-glucose reached much more rapidly a close-to-equilibrium value in isolated islets than in pieces of pancreas obtained from the same donor. The distribution space of D-[3H]mannoheptulose in the human islets largely exceeded that of [U-14C]sucrose, considered as an extracellular marker, and did not differ significantly from that of 3HOH. In the human islets, the heptose (10.0 mM) inhibited both D-[5-3H]glucose utilization and D-[U-14C] glucose oxidation, and decreased glucose-stimulated insulin release to the same extent as D-mannoheptulose hexaacetate. These findings indicate that a suitable radioactive analog of D-mannoheptulose could be used, in human like in rat islets, for preferential labelling of the endocrine moiety of the pancreatic gland.

Carbon Radioisotopes↗

PubMed2001

Uptake of D-mannoheptulose by rat erythrocytes, hepatocytes and parotid cells.

D-[3H]mannoheptulose (or D-[1-14C] mannoheptulose) net uptake was measured in rat erythrocytes, parotid cells and hepatocytes. In the erythrocytes and parotid cells, the intracellular distribution space of the heptose (0.1 mM) represented only about 1 and 13%, respectively, of the intracellular 3HOH space. In hepatocytes, however, it amounted to approximately 45% of the intracellular 3HOH space. In all cases, the apparent distribution space of D-[3H]mannoheptulose hexaacetate largely exceeded that of unesterified D-[3H]mannoheptulose. Relative to the intracellular water space, the generation of acidic metabolites (expressed as an apparent distribution space) from radioactive D-mannoheptulose was one order of magnitude lower in parotid cells (< or = 3%) than in hepatocytes (> or = 20%). These findings are compatible with the hypothesis that D-mannoheptulose is transported into cells mainly, if not exclusively, at the intervention of GLUT2.

Animals↗

PubMed2001

Uptake of tritiated D-mannoheptulose by liver, pancreatic exocrine and endocrine cells.

Tritiated D-mannoheptulose, a ketoheptose known to inhibit D-glucose metabolism in hepatocytes and pancreatic islets, but not so in pancreatic acinar cells, was injected intravenously in streptozotocin-induced diabetic mice transplanted under the kidney capsule with islets from control mice of the same strain. One hour after the injection of the tritiated heptose, the radioactive content was 5-8 times higher in the liver and transplanted islets than in the pancreatic gland. It is proposed that suitably radiolabelled D-mannoheptulose could be used to label preferentially the endocrine moiety of the pancreatic gland, e.g., in the perspective of its non-invasive imaging.

Animals↗

PubMed1988

Boholmycin, a new aminoglycoside antibiotic. I. Production, isolation and properties.

A novel aminoglycoside antibiotic, boholmycin, was produced by Streptomyces hygroscopicus H617-25 isolated from a soil sample collected in Bohol Island, the Philippines. It has a pseudotetrasaccharide structure composed of a heptose, two aminosugars and dicarbamoyl-scyllo-inositol. Intrinsic antibacterial activity of boholmycin is weak but it exhibits broad spectrum activity against Gram-positive and Gram-negative bacteria including aminoglycoside-resistant strains. Boholmycin is non-toxic in mice at 1,000 mg/kg intravenously.

Aminoglycosides↗

PubMed1991

Acclimatization resistance of a Pseudomonas aeruginosa prototype strain to imipenem.

A prototype sensitive strain of Pseudomonas aeruginosa (IRs) was acclimatized in vitro to imipenem by serial transfers in broth containing increasing concentrations of the antibiotic up to 32 micrograms/ml. Serial subculture of the resistant progeny (IR1r) in antibiotic-free solid media resulted in a "revertant" progeny (IR2r) that retained resistance to imipenem. Acclimatization resistance to imipenem and the attempted reversion procedure affected colony morphology, growth rate, pigment production, growth at 42 degrees C and glucose oxidation. SDS-PAGE analysis of the outer membrane proteins revealed in strain IR1r a complete loss of 6 proteins that were present in IRs (85 kdaltons, 46 kdaltons or porin D1, 45.5 kdaltons or porin D2, 43 kdaltons or porin E, 21 kdaltons or protein H1 and 20.5 kdaltons or lipoprotein H2) and in strain IR2r a complete loss of 3 proteins (46 kdaltons, 43 kdaltons, 20.5 kdaltons), while three others were found only in trace amounts (75 kdaltons, 45.5 kdaltons and 21 kdaltons). In the outer membranes of strains IR1r and IR2r an acquisition of a 56-kdalton protein was noted. Lipopolysaccharide chemical analysis revealed a marked, partially reversible increase in 2-keto-3-deoxyoctonate, total hexose and heptose constituents; readily extractable lipid chemical analysis and TLC, revealed a marked, partially reversible, increase in the phospholipid content of the outer membrane. Acclimatization resistance to imipenem was accompanied by cross-resistance to gentamicin, by partially reversible cross-resistance to moxalactam, carbenicillin and ticarcillin and by fully reversible cross-resistance to aztreonam. Sensitivity to azlocillin and polymyxin B remained unaltered. To explain this type of resistance to imipenem, an irreversible, non-inducible "loss" mutation mechanism, working in concert with a partially reversible mechanism, is proposed.

Cell Membrane Permeability↗

PubMed1977

The chemical composition of the lipopolysaccharide from Pseudomonas aeruginosa strain PAO and a spontaneously derived rough mutant.

The chemical composition of the lipopolysaccharide (LPS) of the smooth strain Pseudomonas aeruginosa PAO 307 and a spontaneously derived rough mutant, obtained by selection for resistance to the LPS-specific phage E79, are compared. The rough LPS was shown to contain lipid A, heptose, 2-keto 3-deoxyoctonic acid, galactosamine, alanine and phosphate but lacked glucose, rhamnose and fucosamine which were important constituents, on a weight basis, of the smooth LPS. These results, and chromatographic analysis of the polysaccharide fraction indicate that the rough strain lacked side chain material and was defective in its inner core region. The chemical date obtained were consistent with a core in the PAO strain similar to that of strain NCTC 1999, enhancing the evidence for a common core polysaccharide in the LPS of P. aeruginosa strains.

Bacteriophages↗

PubMedDate not supplied

[Characteristics of lipopolysaccharide from Pseudomonas fluorescens (biovar I)].

Lipopolysaccharide (LPS) of the Pseudomonas fluorescens strain IMV 7769 (biovar I) was isolated and investigated. Fractions of the structural parts of the LPS macromolecule, lipid A, the core oligosaccharide, and the O-specific polysaccharide (O-PS), were obtained in a homogeneous state. 2-Hydroxydecanoic, 3-hydroxydecanoic, dodecanoic, 2-hydroxydodecanoic, 3-hydroxydodecanoic, hexadecanoic, octadecanoic, hexadecenoic, and octadecenoic fatty acids were identified in lipid A. In the hydrophilic moiety of lipid A, after acid hydrolysis, several amino acids, phosphoethanolamine, glucosamine, and three unidentified peaks forming a separate cluster together with glucosamine were found. Lipid A was shown to be phosphorylated. Glucose, fucose, rhamnose, glucosamine, galactosamine, two unidentified amino sugars, 2-keto-3-deoxyoctulonic acid (KDO), heptose, ethanolamine, phosphoethanolamine, and alanine were identified in the core oligosaccharide. O-PS of the LPS consisted of repeating trisaccharide fragments that included residues of amino sugars: 4-acetamido-4,6-dideoxy-D-galactose, 2-acetamido-2,6-dideoxy-D-glucose, and 2-acetamido-2,6-dideoxy-L-glucose. During growth, the strain under study excreted exocellular LPS (ELPS) into the medium. The LPS studied was similar to the LPS of the earlier investigated strains P. fluorescens (biovar I) IMV 1152 and IMV 1433 in the structure of O-PS, but differed from them in the composition of both lipid A and the core oligosaccharide. The LPS of the strain studied differed from LPS of the type strain P. fluorescens IMV 4125 (ATCC 13525) in all characteristics determined.

Chromatography, Gas↗

PubMed1999

Chemical characterization of the lipopolysaccharides from enteropathogenic Escherichia coli O142 and O158.

Lipopolysaccharides (LPS) from two enteropathogenic strains of E. coli O142 and O158 were isolated by hot phenol-water extraction procedure. Polyacrylamide gel electrophoretic pattern of the LPS showed the typical ladder like pattern of smooth type of LPS. The LPS of E. coli O158 was found to contain L-rhamnose, D-glucose and N-acetyl-D-galactosamine as major constituents together with D-galactose, N-acetyl-D-glucosamine, L-glycero-D-manno-heptose and 2-keto-3-deoxy-D-manno-octulosonic acid (KDO) whereas LPS from E. coli O142 contained L-rhamnose, N-acetyl-D-glucosamine and N-acetyl-D-galactosamine as major constituents together with D-glucose, D-galactose, N-acetyl-D-glucosamine, L-glycero-D-mannoheptose and 2-keto-3-deoxy-D-manno-octulosonic acid (KDO). LPS was degraded by mild acid hydrolysis to yield a degraded polysaccharide fraction and an insoluble lipid-A fraction. The main fatty acids of the lipid-A fraction of the LPS were C12:O, C14:O, and 3-OH C14:O for O158 strain whereas E. coli O142 lipid-A consisted of C12:O, C14:O, 3-OH C14:O, and C16:O. The degraded polysaccharide fraction on gel permeation chromatography gave a high moleculer weight O-chain fraction and a core oligosaccharide and a fraction containing degraded sugars. The chemical composition of LPS and its fragmented products are reported in this communication.

Animals↗

PubMed1999

Chemical composition of endotoxins produced by Fusobacterium necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme.

The endotoxins from two recently-classified subspecies of Fusobacterium, namely F. necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme, were compared. Chemical analysis of the isolated endotoxins revealed that they were clearly different. Distinct levels of polysaccharides were demonstrated. The endotoxins isolated were devoid of heptose and 3-deoxy-D-manno-octulosonate (KDO). The endotoxins of F. n. necrophorum and F. n. funduliforme contained lipid A in a ratio of 4:1 which may account for the variations in their virulence.

Endotoxins↗

PubMed1978

Immunochemical studies on a Yersinia enterocolitica O:9 lipopolysaccharide cross-reacting with Brucella abortus and Vibrio cholerae extracts.

The presence of two distinct lipopolysaccharides in Yersinia enterocolitica O:9 is described: one isolated from the aqueous phase and one from the phenol phase (Westphal system). The sugar moiety of the phenol phase lipopolysaccharide has been identified as being responsible for the serologic cross-reaction of Y. enterocolitica O:9, Brucella abortus and Vibrio cholerae. The phenol phase antigen consists of glucose, galactose, glucosamine, 2-keto-3-deoxyoctonic acid, heptose, lipid A and a protein moiety. Haemagglutination experiments revealed two different structures: one that readily coats erythrocytes and another that requires alkali treatment. The former may be separated by repeated adsorptions on erythrocytes. Serologically, the two structures behave like a single antigen. The action of normal rabbit serum on the erythrocyte-containg capacity of the two structures was studied.

Animals↗

PubMed1999

Chemical characterization of effective and ineffective strains of Rhizobium leguminosarum bv. viciae.

Chemical composition of lipopolysaccharide (LPS) isolated from an effective (97) and ineffective (87) strains of R. l. viciae has been determined. LPS preparations from the two strains contained: glucose, galactose, mannose, fucose, arabinose, heptose, glucosamine, galactosamine, quinovosamine, and 3-N-methyl-3,6-dideoxyhexose, as well as glucuronic, galacturonic and 3-deoxyoctulosonic acid. The following fatty acids were identified: 3-OH 14:0, 3-OH 15:0, 3-OH 16:0, 3-OH 18:0 and 27-OH 28:0. The ratio of 3-OH 14:0 to other major fatty acids in LPS 87 was higher that in LPS 97. SDS/PAGE profiles of LPS indicated that, in lipopolysaccharides, relative content of S form LPS I to that of lower molecular mass (LPS II) was much higher in the effective strain 97 than in 87. All types of polysaccharides exo-, capsular-, lipo, (EPS, CPS, LPS, respectively) examined possessed the ability to bind faba bean lectin. The degree of affinity of the host lectin to LPS 87 was half that to LPS 97. Fatty acids (FA) composition from bacteroids and peribacteroid membrane (PBM) was determined. Palmitic, stearic and hexadecenoic acids were common components found in both strains. There was a high content of unsaturated fatty acids in bacteroids as well as in PBM lipids. The unsaturation index in the PBM formed by strain 87 was lower than in the case of strain 97. Higher ratio of 16:0 to 18:1 fatty acids was characteristic for PMB of the ineffective strain.

Carbohydrates↗

PubMed2001

Assessment by D-[(3)H]mannoheptulose uptake of B-cell density in isolated pancreatic islets from Goto-Kakizaki rats.

The uptake of D-[3H]mannoheptulose by isolated pancreatic islets was recently proposed as a tool to assess the relative contribution of insulin-producing cells to the total mass of the islets. In the present study, the uptake of the tritiated heptose over 60 min incubation at 37 degrees C was about 21% lower in islets from hereditarily diabetic rats (GK rats) than in islets from control animals, this decrease being virtually identical to that documented previously by morphometric analysis of islets from the same type of rats. The intracellular 3HOH space and extracellular [U-14C]sucrose space were not significantly different in control and diabetic rats, at least when the comparison was restricted to animals of the same sex. There was a trend, however, towards a somewhat lower D-[5-3H]-glucose intracellular distribution space in islets from GK rats, as compared to control animals. These findings provide further support to the validity of D-[3H]mannoheptulose uptake as a tool to assess the density of insulin-producing cells in isolated islets.

Animals↗

PubMed2001

Cloning, sequencing, and functional analysis of three glycosyltransferases involved in the biosynthesis of the inner core region of Klebsiella pneumoniae lipopolysaccharide.

The genes encoding the 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) transferase (waaA) and heptosyltransferases I (waaC) and II (waaF) in Klebsiella pneumoniae were cloned from a DNA library by functional complementation of corresponding Escherichia coli and Salmonella enterica mutants. Sequence analyses revealed extensive homologies of the deduced proteins to their counterparts in other Enterobacteriaceae. However, differences were evident with regard to the chromosomal organization of the genes. To perform in vitro studies, the waaA, waaC and waaF genes were subcloned and expressed in the Gram-positive host Corynebacterium glutamicum. WaaA was characterized as a bifunctional enzyme capable of transferring two Kdo residues to a synthetic bisphosphorylated tetraacyl-lipid A precursor of E. coli (compound 406). In contrast, waaC and waaF were shown to encode specific glycosyltransferases catalyzing the consecutive transfer of two L-glycero-D-manno-heptose residues to Kdo(2)-406.

Carbohydrate Sequence↗

PubMedDate not supplied

[Comparative characteristics of lipopolysaccharides of various Pseudomonas fluorescens strains (Biovar I)].

From the biomass of five Pseudomonas fluorescens biovar I strains, including the P. fluorescens type strain IMV 4125 (ATCC 13525), lipopolysaccharides (LPS) were isolated (by extraction with a phenol-water mixture followed by repeated ultracentrifugation), as well as individual structural components of the LPS macromolecule: lipid A, the core oligosaccharide, and O-specific polysaccharide (O-PS). 3-Hydroxydecanoic, 2-hydroxydodecanoic, 3-hydroxydodecanoic, dodecanoic, hexadecanoic, octadecanoic, hexadecenoic, and octadecenoic fatty acids were present in lipid A of the LPS of all the strains studied. Glucosamine, ethanolamine, and phosphoethanolamine were revealed in the lipid A hydrophilic part of all of KDO, a trace amount of heptoses, ethanolamine, phosphoethanolamine, alanine, and phosphorus were identified as the main core components. Interstrain differences in the core oligosaccharide composition were revealed. Structural analysis showed that the O-PS of the type strain, as distinct from that of other strains, is heterogeneous and contains two types of repetitive units, including (1) three L-rhamnose residues (L-Rha), one 3-acetamide-3,6-dideoxy-D-galactose residue (D-Fuc3NAc) as a branching substitute of the L-rhamnan chain and (2) three L-Rha residues and two branching D-Fuc3NAc residues. The type strain is also serologically distinct from other biovar I strains due to the LPS O-chain structure, which is similar to those of the strains of the species Pseudomonas syringae, including the type strain. The data of structural analysis agree well with the results of immunochemical studies of LPS.

Lipopolysaccharides↗

PubMedDate not supplied

[Diversity in the monosaccharide composition of antigenic polysaccharides from proteobacteria Pseudoalteromonas and Marinomonas genera].

The sugar analysis of the glycans of the type strains of marine proteobacteria of the genera Pseudoalteromonas and Marinomonas--Pseudoalteromonas atlantica IAM12927T, P. aurantia NCIMB 2033T, P. citrea ATCC 29719T, P. elyakovii KMM 162T, P. espejiana ATCC 29659T, P. piscicida NCIMB 645T, P. tetraodonis IAM 14160T, Marinomonas communis ATCC 27118T, and M. vaga ATCC 27119T--showed that they contain glucose, galactose, galactosamine, glucosamine, fucose, rhamnose, mannose, heptose, 2-keto-3-deoxyoctonate (KDO), uronic acids, colitose (3,6-dideoxyl-L-xylo-hexose), and 6-deoxy-L-talose. The carbohydrate composition of the antigenic polysaccharides (PSs) of P. elyakovii KMM 162T and P. espejiana ATCC 29659T depended on the type and the concentration of carbohydrate substrates in the nutrient media. The molar proportion between rhamnose, glucose, and galactose (ca. 1:0.3:2) in the PS of P. elyakovii KMM 162T was almost the same in the media lacking carbohydrates or containing glucose or galactose at a concentration of 1 g/l. At the same time, the molar proportion between fucose, glucose, galactose, galactosamine, and glucosamine (ca. 1:1:1:2:0.5) in the PS of P. espejiana ATCC 29659T depended on the presence and the concentration of carbohydrate substrates in the medium. A high concentration of glucose in the medium (30 g/l) brought about a rise in the content of glucose in PSs (9-fold for the PS of P. elyakovii KMM 162T and 4.6-fold for the PS of P. espejiana ATCC 29659T) and led to a decrease in the content of other carbohydrates. The cultivation of these two strains at a lactose concentration of 30 g/l resulted in their PSs containing glucose and galactose in about equal proportions (ca. 1:1 in the case of P. espejiana ATCC 29659T and ca. 2.1:1.7 in the case of P. elyakovii KMM 162T).

Antigens, Bacterial↗

PubMed1992

[Chemical analysis of lipopolysac-charides derived from oral anacerobes]

Lipopolysaccharides were isolated from six oral anaerobes(Va.Bg.Bf.Fn.Aa.Co.)by the hot phenol-water procedure and purified by PCP method.The six species can be all extracted their LPS with different yields (from 0.70 to 2.83% of cell dried weight).Comparable of LPS with the enterobacteriaceae(Sm.),they were the constructed with hexosamine,fatty acids and phosphorus etc.On the other hand,they showed much distinct differences from the enterobacterial LPS structure as follow:(1) 2-keto-3-deoxy-D-mannooctonate(KDO) was not detected by routine procedure.(2)The amount of heptose is reltively lower.(3) Methylated and branched fatty acids were detected.These chemical characteristics may relate to biological activities and pathogenic potential of LPS and bacteria themselves.

Journal Article↗