Detection of 3-deoxy-2-octulosonic acid in thiobarbiturate-negative endotoxins

Characterization of the Salmonella Typhimurium core oligosaccharide and its reducing end 3-deoxy-d-manno-oct-2-ulosonic acid used for conjugate vaccine production

One of the strategies adopted for the development of a bivalent conjugate vaccine against invasive nontyphoidal Salmonella consists of linking the O-antigen component of S. Typhimurium and S. Entertidis lipopolysaccharides to the carrier protein CRM₁₉₇, a non-toxic variant of diphtheria toxin. The conjugation reaction uses the reducing end residue 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) of the core to which the O-antigen chain is bound (OAg-core). OAg-core chains are cleaved from the lipid A directly in the fermentation broth by mild acid treatment. Kdo has been reported to undergo structural changes under these conditions and therefore the Kdo at the reducing end was thoroughly analysed to verify its structural integrity. For this purpose, low molecular mass OAg-core chains extracted from S. Typhimurium wild type bacteria and core oligosaccharides extracted from S. Typhimurium bacteria mutated not to produce O-antigen repeats were characterized by GLC-MS, MALDI-TOF-MS and NMR spectroscopy. Moreover, a combination of ¹H-¹H and ¹H-¹³C experiments confirmed the linkage positions, sequence and structure of the octasaccharide core with 5-linked Kdo present at the reducing end in its native structure: α-GlcpNAc-(1→2)-α-Glcp-(1→2)-α-Galp-(1→3)-[α-Galp-(1→6)]-α-Glcp-(1→3)-[α-Hepp-(1→7)]-α-Hepp-(1→3)-α-Hepp-(1→5)-Kdo.

LPS quantitation procedures

Lipopolysaccharide is the predominant component of the Gram-negative cell wall occupying the outer leaflet of the outer membrane of Pseudomonas aeruginosa. Wild-type bacteria produce smooth LPS composed of lipid A, core oligosaccharide, and long O-antigen polysaccharide. In contrast, mutant bacteria defective in LPS biosynthesis produce rough LPS lacking the long O-antigen side chains. LPS is also a major virulence factor and proven to be crucial for full elaboration of other virulence factors and for a range of cellular functions. In order to determine the relationship between LPS and other cellular functions, a means to measure changes in the quantities of LPS being produced under certain growth/environmental conditions is important. Hence, the objective of this chapter is to provide readers with the methodologies for analyzing LPS of P. aeruginosa both qualitatively and quantitatively. As a prerequisite to quantifying LPS, one must be able to isolate LPS from the cell envelope; therefore, Subheading 2.1 is devoted to describing several standard LPS preparation methods. This is followed by Subheading 2.2, which deals with a number of practical methods for analyzing and/or quantifying whole-molecule LPS or assays for quantifying specific sugar constituents that are present within P. aeruginosa LPS. The methods described herein should be broadly applicable to the studying of LPS of other pseudomonads as well as Burkholderia species.

The chemical composition of endotoxin isolated from intestinal strain of Desulfovibrio desulfuricans

Desulfovibrio desulfuricans anaerobes are constituents of human alimentary tract microflora. There are suggestions that they take part in the pathogenesis of periodontitis and some gastrointestinal inflammatory disorders, such as ulcerative colitis or Crohn's disease. Endotoxin is one of Gram-negative bacteria cellular components that influence these microorganisms pathogenicity. Endotoxin is a lipid-polisaccharide heteropolymer consisting of three elements: lipid A, core oligosaccharide, and O-specific polysaccharide, also called antigen-O. The biological activity of lipopolysaccharide (LPS) is determined by its structure. In this study, we show that rhamnose, fucose, mannose, glucose, galactose, heptose, and 2-keto-3-deoxyoctulosonic acid (Kdo) are constituents of D. desulfuricans endotoxin oligosaccharide core and O-antigen. Lipid A of these bacteria LPS is composed of glucosamine disaccharide substituted by 3-acyloxyacyl residues: ester-bound 3-(dodecanoyloxy)tetradecanoic, 3-(hexadecanoyloxy)tetradecanoic acid, and amide-bound 3-(tetradecanoyloxy)tetradecanoic acid.

Determination of distinctive carbohydrate signatures obtained from the Aeromonas hydrophila (chemotype II) core oligosaccharide pinpointing the presence of the 4-O-phosphorylated 5-O-linked Kdo reducing end group using electrospray ionization quadrupole orthogonal time-of-flight mass spectrometry and tandem mass spectrometry

The electrospray quadrupole orthogonal time-of-flight mass spectrometric (ESI-QqTOF-MS) structural elucidation of the core oligosaccharide of Aeromonas hydrophila (chemotype II) lipopolysaccharide has been investigated and it was demonstrated that it contained an 4-O-phosphorylated Kdo reducing end group, which was glycosylated by the remaining outer core oligosaccharide through its O-5 position. After releasing the core oligosaccharide from the native LPS with acid, the phosphorylated Kdo residue eliminated phosphoric acid, to produce a core oligosaccharide containing a mixture of diastereomeric 4,8- and 4,7-anhydro-alpha-keto acids and an open-chain olefinic Kdo residue. The characteristic glycone sequence was elucidated by collision-induced dissociation tandem mass spectrometry (CID-MS/MS) of the protonated molecule of the native core oligosaccharide. In addition, the analysis of the Hakomori permethylated core oligosaccharide was carried out by electrospray ionization quadrupole orthogonal time-of-flight mass spectrometry (ESI-QqTOF-MS) and matrix-assisted laser desorption/ionization (MALDI)-QqTOF-MS analyses. The presence of more than nine isobaric isomers of this core was detected. The CID-MS/MS analysis of the various protonated permethylated core oligosaccharide molecules showed a similar and diagnostic fragmentation pattern. The over-methylation of the permethylated core oligosaccharide containing either the 4,7- or the 4,8-anhydro-alpha-keto acid unit and the open-chain olefinic Kdo unit was reported. It was realized that the extra minor satellite signals obtained in the ESI-QqTOF-MS and MALDI-TOF-MS analyses were dimethyl sulfoxide (DMSO) stable covalent addition products, which have occurred by a Michael addition on the 4,8-Kdo exocyclic double bond. The occurrence of this series of covalent addition products during the MS analysis of a permethylated core oligosaccharide should be considered as 'carbohydrate-distinctive signatures' establishing and confirming the presence of a 4-O-phosphorylated-5-O-linked Kdo reducing end group.

Structural reinvestigation of the core oligosaccharide of a mutant form of Aeromonas salmonicida lipopolysaccharide containing an O-4 phosphorylated and O-5 substituted Kdo reducing end group using electrospray QqTOF-MS/MS

The molecular structure of the mutant form of the lipopolysaccharide of Aeromonas salmonicida was determined to contain an O-4 phosphorylated and O-5 substituted Kdo reducing group, and is proposed as the following: [molecular structure: see text] It was established that during the cleavage of this LPS with 1% acetic acid, to release the core oligosaccharide from the Lipid A portion, we obtained a degraded core oligosaccharide which eliminated its phosphate group with extreme facility. The precise molecular structure of this dephosphorylated core was deduced by electrospray mass spectrometry and is proposed as the following:[molecular structure: see text] Low energy collision ESI-QqTOF-MS/MS analysis of the dephosphorylated core oligosaccharide confirmed the presence of the O-5 glycosylated 4,8- and 4,7-anhydro derivatives of the enolizable alpha-keto-acids. The CID tandem mass spectrometric analysis of the heterogeneous mixture of the permethylated core oligosaccharide established the unreported methylation reaction on the diastereomeric 4,8- and 4,7-anhydro alpha-keto-acids and the complete permethylation and addition reaction of the O-5 glycosylated open chain reducing end terminal D-arabino-3-en-2-ulonic acid. The stereo-specific fragmentation routes obtained during the tandem mass spectrometric analysis permitted the precise sequencing of this dephosphorylated rough core oligosaccharide of the mutant LPS of A. salmonicida.

Characterization of the O-4 phosphorylated and O-5 substituted Kdo reducing end group and sequencing of the core oligosaccharide of Aeromonas salmonicida ssp salmonicida lipopolysaccharide using tandem mass spectrometry

The molecular structure of the wild strain of the lipopolysaccharide core of Aeromonas salmonicida, ssp salmonicida has been sequenced using tandem mass spectrometry. The core oligosaccharide was determined to contain an O-4 phosphorylated and O-5 substituted Kdo reducing group, and its structure is proposed as the follows: [structure: see text] After the core oligosaccharide of LPS was released from the lipid A portion by conventional treatment with 1% acetic acid, we demonstrated the existence of a homogeneous mixture composed mainly of the native core oligosaccharide containing the Kdo with its O-4 phosphate group intact, and a degraded core oligosaccharide mixture, which eliminated the O-4 phosphate group with extreme facility. The precise molecular structure and glycone sequence of the homogeneous mixture of phosphorylated and dephosphorylated core oligosaccharides was determined by electrospray ionization (ESI) mass spectrometry and tandem mass spectrometric analysis. CID-MS/MS of the homogeneous mixture of permethylated core oligosaccharides afforded a series of diagnostic product ions which confirmed the established sequence of the glycones to be determined. Matrix-assisted laser desorption/ionization (MALDI) tandem mass spectrometry reconfirmed the molecular structure of the dephosphorylated homogeneous permethylated mixture of the core oligosaccharides containing the diastereomeric 4,8- and 4,7-anhydro-alpha-keto acids.

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.

Chemical and serological characterization of the Bordetella hinzii lipopolysaccharides

Bordetella hinzii has recently been isolated from immunocompromised human hosts. The polysaccharides isolated from its endotoxin (lipopolysaccharide, LPS) were investigated using chemical analyses, NMR, gas-liquid chromatography/mass spectrometry and mass spectrometry by plasma desorption, matrix-assisted laser desorption/ionization and electrospray. The following structure for the O-chain-free LPS was deduced from the experimental results: carbohydrate structure [see text] Mass spectrometry and serology revealed that the O-chains were different from the homopolymer common to Bordetella bronchiseptica and Bordetella parapertussis strains and were composed of a trisaccharide repeating unit. Masses up to 8 kDa were obtained for native LPS molecular species.

Structure of the Bordetella pertussis 1414 endotoxin

The endotoxin (lipopolysaccharide) of Bordetella pertussis, the agent of whooping cough, consists of a lipid A linked to a highly branched dodecasaccharide containing several acid and amino sugars. The elucidation of the polysaccharide structure was accomplished by first analyzing the structures of fragments obtained by hydrolysis and nitrous deamination and then piecing the fragments together. The fine structure of the antigenic distal pentasaccharide, presented here, was determined by chemical analyses as well as by high-resolution nuclear magnetic resonance and mass spectrometry. The complete structure was reconstituted and confirmed by matrix-assisted laser desorption/ionization mass spectrometry. The following structure was derived from the combined experimental data:The detailed structure combined with previously reported serological data now allows the synthesis of its epitopes for potential vaccines.

Quantification of bacterial lipopolysaccharides by the purpald assay: measuring formaldehyde generated from 2-keto-3-deoxyoctonate and heptose at the inner core by periodate oxidation

We have adapted the purpald assay (M. S. Quesenberry and Y. C. Lee, Anal. Biochem. 234, 50-55, 1996) to quantify lipopolysaccharide (LPS) content in solution in 96-well microtiter plates at room temperature. This method employs the oxidation of unsubstituted terminal vicinal glycol groups in 2-keto-3-deoxyoctonate (Kdo) and l-(or d-)glycero-d-manno-heptose of LPS molecules by periodate to release formaldehyde. The formaldehyde is quantified at 550 nm (or 530-570 nm) by reacting with purpald reagent followed by oxidation with NaIO4. The sensitivity of the purpald assay is comparable to that of the Kdo assay for LPS determination. However, the purpald assay is superior to the Kdo assay because: (i) No acid hydrolysis of the samples and no boiling in the assay process are required; thus, it can be directly carried out with microtiter plates for a large number of samples at room temperature. (ii) The purpald assay can detect many types of LPS from various bacteria since LPS contains Kdo and heptose which possess unsubstituted terminal vicinal glycol in its structure, while the Kdo assay cannot detect LPS from certain bacteria (e.g., Haemophilus influenzae, Bordetella pertussis, and Vibrio cholerae) due to substitution at the C-4 and C-5 positions of Kdo.

A mono-functional 3-deoxy-D-manno-octulosonic acid (Kdo) transferase and a Kdo kinase in extracts of Haemophilus influenzae

Lipopolysaccharide of Haemophilus influenzae contains a single 3-deoxy-D-manno-octulosonic acid (Kdo) residue, linked to the 6' position of lipid A. In Escherichia coli and related organisms, a Kdo disaccharide is attached to lipid A. In previous studies, we cloned the gene (kdtA) encoding the E. coli Kdo transferase and demonstrated that homogeneous preparations of KdtA polypeptide catalyzed the attachment of both Kdo groups to the precursor, lipid IVA. E. coli KdtA produced only traces of mono-glycosylated product. We now show that a single Kdo is transferred to lipid IVA in extracts of H. influenzae. The mono-functional Kdo transferase of H. influenzae is membrane-bound, and the reaction is dependent upon a CMP-Kdo-generating system, as in E. coli. The specific activity of Kdo transfer to lipid IVA is 0.5-1 nmol/min/mg in H. influenzae membranes. Utilizing solubilized H. influenzae membranes, milligram quantities of Kdo-lipid IVA were prepared for analysis. Matrix-assisted laser desorption/ionization mass spectrometry revealed a parent ion (M - H)- at m/z 1626.0, consistent with the addition of a single Kdo moiety. Like lipid IVA, Kdo-lipid IVA was an excellent substrate for the bi-functional Kdo transferase of E. coli. In membranes of H. influenzae, but not E. coli, Kdo-lipid IVA was further phosphorylated in the presence of ATP, yielding a mono-phosphorylated Kdo-lipid IVA with a parent ion (M - H)- at m/z 1703.9. The identification of the mono-functional H. influenzae Kdo transferase, which is encoded by a KdtA homologue that displays 50% identity to its E. coli counterpart, should facilitate the mechanistic dissection of more complex multi-functional Kdo transferases, like those of E. coli and Chlamydia trachomatis.

The tetrasaccharide L-alpha-D-heptose1-->2-L-alpha-D-heptose1--> 3-L-alpha-D-heptose1-->(3-deoxy-D-manno-octulosonic acid) and phosphate in lipid A define the conserved epitope in Haemophilus lipopolysaccharides recognized by a monoclonal antibody

A murine monoclonal antibody, MAHI 3 (immunoglobulin G2b), that is broadly reactive with Haemophilus influenzae lipopolysaccharides (LPSs) but nonreactive with all enterobacterial LPSs tested was generated by fusing mouse myeloma cells with spleen cells of BALB/c mice immunized with azide-killed H. influenzae RM.7004. MAHI 3 bound to all H. influenzae, all other human Haemophilus spp., all Bordetella pertussis and Bordetella parapertussis, and all Aeromonas spp. tested but not to any Neisseria or Moraxella catarrhalis strains, as determined by enzyme immunoassay, colony dot immunoblotting, and immunoblotting. In an inhibition enzyme immunoassay, MAHI 3 reacted with all 45 H. influenzae LPSs tested but not with the LPS from the rough mutant I69 Rd-/b+, which has only 3-deoxy-D-manno-octulosonic acid (P) [Kdo(P)] and lipid A. The antibody was not inhibited by H. influenzae lipid A or lipid-free polysaccharide isolated after mild acid hydrolysis. Only native LPSs show positive inhibitory activity, indicating that part of lipid A is involved in the binding of MAHI 3. From the results, it is indicated that the structural element recognized by MAHI 3 is Hep alpha 1-->2Hep alpha 1-->3Hep alpha 1-->Kdo together with part of lipid A, including the phosphate.

Structure of a hexasaccharide proximal to the hydrophobic region of lipopolysaccharides present in Bordetella pertussis endotoxin preparations

A branched-chain hexasaccharide containing 3-deoxy-D-manno-oct-2-ulosonic acid was released by detergent-promoted hydrolysis from Bordetella pertussis endotoxin preparations that were first dephosphorylated with aqueous HF and then treated with nitrous acid. Its structure (2) [Formula: See text] was determined by chemical and physical methods. This hexasaccharide is present in all four lipopolysaccharides that make up the B. pertussis strain 1414 (phase 1) endotoxin preparations analysed, and is situated near to the hydrophobic domains. An analogous structure reported previously (ref 7) is erroneous and should be disregarded.

Porins and lipopolysaccharide of Escherichia coli ATCC 25922 and isogenic rough mutants

The lipopolysaccharide and porin profile of Escherichia coli ATCC 25922, a smooth strain commonly used in antibiotic susceptibility testing, and five isogenic rough mutants was examined. The lipopolysaccharide of the parent strain had the characteristic ladder pattern on polyacrylamide gels, while that of the mutants appeared similar to chemotypes Ra and Rc of Salmonella typhimurium with some changes in chemical composition. Of the porins, OmpC appeared markedly reduced in the parent strain while OmpF appeared markedly reduced in the mutants. In addition, a new outer-membrane protein of size intermediate to that of OmpC and OmpF was detected in all mutants. Neither parent nor mutants were susceptible to the LPS core-specific P1 phage or the porin-specific PA2 and K20 phages.

Preparation and binding specificity of a monoclonal antibody recognizing 3-deoxy-D-manno-2-octulosonic acid (Kdo) in lipopolysaccharides of Re chemotype

A mouse monoclonal antibody (MAb E1) was raised against the lipopolysaccharide (LPS) of the Re mutant R595 of Salmonella minnesota. This IgG3 antibody (MAb E1), unstable at low pH and low ionic strength, was purified by chromatography on QAE Sepharose A50. The binding specificity of MAb E1 was characterized by direct and inhibition enzyme immunoassays, using natural LPSs from different strains and chemotypes, and synthetic analogs of LPS substructure of the 3-deoxy-D-manno-2-octulosonic acid (Kdo) and Lipid A regions. Among various LPSs, MAb E1 reacted exclusively with those of Re-chemotype. It recognized alpha-Kdo- monosaccharide and disaccharide structures present as non-reducing side chains in various Re-type LPSs and synthetic antigens. The antibody did not react with Lipid A or various lipids, and the presence of the lipid region was not necessary for the reaction. The recognition of the epitope was not reduced by the presence of a substituent at O-8 of one of the two Kdo units present in the Re LPS from Proteus mirabilis, but the reaction was inhibited by phosphorylation of O-4 of Kdo, by the proximity of core (heptose) or Lipid A (acylated glucosamine) residues, or by certain LPS-LPS interactions.

Structural characterization of the cell surface lipooligosaccharides from a nontypable strain of Haemophilus influenzae

Oligosaccharides released from the lipooligosaccharides (LOS) of Haemophilus influenzae nontypable strain 2019 by mild acid hydrolysis were fractionated by size exclusion chromatography and analyzed by liquid secondary ion mass spectrometry. The major component of the heterogeneous mixture was found to be a hexasaccharide of Mr 1366, which lost two phosphoethanolamine groups upon treatment with 48% aqueous HF. The dephosphorylated hexasaccharide was purified and shown by tandem mass spectrometry, composition analysis, methylation analysis, and two-dimensional nuclear magnetic resonance studies to be Gal beta 1----4Glc beta 1----(Hep alpha 1----2Hep alpha 1----3) 4Hep alpha 1----5anhydro-KDO, where Hep is L-glycero-D-manno-heptose and KDO is 3-deoxy-D-manno-octulosonic acid. An analogous structure containing authentic KDO was generated from LOS that had been HF-treated prior to acetic acid hydrolysis, suggesting that the reducing terminal anhydro-KDO moiety is produced as an artifact of the hydrolysis procedure by beta-elimination of a phosphate substituent from C-4 of KDO. Mass spectral analyses of O-deacylated LOS and free lipid A confirmed that, in addition to the two phosphoethanolamines on the oligosaccharide and two phosphates on the lipid A, another phosphate group exists on the KDO. This KDO does not appear to be further substituted with additional KDO residues in intact H. influenzae 2019 LOS. The terminal disaccharide epitope, Gal beta 1----4Glc beta 1----, of the hexasaccharide is also present on lactosylceramide, a precursor to human blood group antigens. It is postulated that the presence of this structure on H. influenzae LOS may represent a form of host mimicry by the pathogen.

Chemical structure of the carbohydrate backbone of Vibrio parahaemolyticus serotype 012 lipopolysaccharide

The chemical structure of the saccharide portion of Vibrio parahaemolyticus serotype 012 lipopolysaccharide was studied. Using chemical degradation and modification, as well as methylation analysis in combination with GLC-MS, laser-desorption mass spectrometry and 1H-NMR and 13C-NMR spectroscopy, the carbohydrate backbone of the lipopolysaccharide was characterized as a branched decasaccharide with the following structure: (formula; see text) In the native lipopolysaccharide two additional phosphate groups are present and 3-deoxy-D-threo-hexulosonic acid and D-galacturonic acid are bound via acid-labile linkages.

Ionizing groups in lipopolysaccharides of Pseudomonas cepacia in relation to antibiotic resistance

Contrary to previous reports, lipopolysaccharides from Pseudomonas cepacia contain a 3-deoxyoct-2-ulosonic acid (probably a single residue). The lipopolysaccharides contain only two phosphate residues, one of which apparently forms a phosphodiester bridge between 4-amino-4-deoxyarabinose and a glucosamine residue in lipid A. The second, unlocated phosphate residue occurs mainly as a monoester in some lipopolysaccharides, and mainly as a diester in others. All lipopolysaccharides lack pyrophosphate residues. The results support the view that the resistance of P. cepacia to cationic antibiotics stems from ineffective binding to the outer membrane, as a consequence of the low number of phosphate and carboxylate groups in the lipopolysaccharide, and the presence of the protonated aminodeoxypentose.

Structural models for the cell surface lipooligosaccharides of Neisseria gonorrhoeae and Haemophilus influenzae

A structural model is proposed for the surface glycolipids, or lipooligosaccharides (LOS), of gram-negative pathogenic bacteria that colonize human mucosae, e.g. Neisseria gonorrhoeae and Haemophilus influenzae. The development of this model has involved analysis of a series of pyocin-resistant mutants with altered LOS and other recent immunochemical and structural data. A comprehensive approach to determining the necessary structural data has been constructed that utilizes liquid secondary ion mass spectrometry, tandem mass spectrometry, methylation analysis and nuclear magnetic resonance. To prepare purified oligosaccharides for these analyses, chromatographic and chemical techniques have been developed that include high-pH anion-exchange chromatography of underivatized oligosaccharides and reverse-phase chromatography after derivatization with hydrazino alkyl benzoates. The proposed LOS model has several unique features that distinguish it from models developed for the lipopolysaccharides of enteric bacteria. This information should lead to an understanding of the unique structure/function relationship of LOS and to the development of carbohydrate-based vaccines.

Variations in the carbohydrate regions of Bordetella pertussis lipopolysaccharides: electrophoretic, serological, and structural features

Structural and immunological differences between the two components that are usually present in unequal quantities in Bordetella pertussis endotoxin preparations and are visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis have been studied by using strains 1414, A100, and 134, all in phase I. According to analyses by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and thin-layer chromatography, the minor (8%) component of the endotoxin of strain 1414 (endotoxin 1414) appeared to be the predominating component of endotoxins A100 and 134. The masses of the carbohydrate chains isolated from endotoxin A100 and from the major component of endotoxin 1414 were 1,649 and 2,311 atomic mass units, respectively, as determined by 252Cf plasma desorption mass spectrometry. Comparison of the 1H nuclear magnetic resonance spectra of these chains established that four N-acetyl groups, an N-methyl group, and a 6-deoxy function, which characterize the nonreducing, distal trisaccharide of the glycose chain of strain 1414, were absent from that of strain A100. The antigenicity of endotoxin 1414, as measured by enzyme-linked immunosorbent assay, was higher than that of endotoxin A100, but fell below it when the glycose chain of endotoxin 1414 was deprived of seven sugars by treatment with nitrous acid. This observation suggests that at least three (distal, proximal, and intermediate) regions of the glycose chain of endotoxin 1414 carry antigenic determinants. One of these, located in the distal trisaccharide, is absent from both endotoxins A100 and 134.

Chemical characterization and biologic properties of lipopolysaccharide from Bacteroides gingivalis strains W50, W83, and ATCC 33277

The chemistry and selected biological activity of lipopolysaccharide (LPS) from Bacteroides gingivalis strains W50, W83, and ATCC 33277 were compared, as well as the role of this molecule as a mediator of selected inflammatory responses. Chemically, the LPSs consisted of 47-58% Lipid A, 5-10% carbohydrate, 0.05% 3-deoxy 2-octulosonic acid, 0.3% heptose, 3.8-5.2% hexosamine, and 2% phosphate. Rhamnose represented the dominant sugar (26-36%), with lesser amounts of glucose (18-34%), galactose (18-25%), mannose (9-12%), glucosamine (7-11%), and galactosamine (2-5%). The major fatty acids were: 13-methyl-tetradecanoate (42-45%), 3-OH-heptadecanoate (21-23%), hexadecanoate (16-19%), and 12-methyl-tetradecanoate (6-8%). SDS-PAGE and sodium deoxycholate-PAGE revealed the LPS to be a smooth chemotype. Differences in migration patterns between the virulent and avirulent strain LPSs also occurred. C3H/HeN macrophages (Mø) exposed to 1 microgram/ml of LPS released 3.2-4.2 ng of prostaglandin E (PGE)/ml of supernatant, representing 236-278% of control. Interleukin-1 (IL-1) activity in C3H/HeN and C3H/HeJ Mø exposed to 50 micrograms of LPS/ml was 382-724% and 270-300% of control, respectively; similar Mø exposed to 10 micrograms of LPS/ml released 1.6-2.0 ng and 0.3-0.5 ng of tumor necrosis factor (TNF)/ml of supernatant, respectively. Maximum TNF release in C3H/HeN Mø occurred in response to 50 micrograms of LPS/ml, and was sustained for up to 96 hours. These results suggest that LPS from the B. gingivalis strains stimulate cytokine production from Mø which, in turn, may play a role in orchestrating the inflammatory response for the development of periodontal diseases.

Occurrence of a common lipopolysaccharide antigen in standard and clinical strains of Pseudomonas aeruginosa

The lipopolysaccharide (LPS) of Pseudomonas aeruginosa PAO1 contains two species of O polysaccharide termed A and B bands. The high-molecular-weight B-band LPS determines the O specificity of the bacterium, while the antigenically distinct A-band LPS consists of only shorter-chain polysaccharides. Seven hybridomas secreting A-band-specific monoclonal antibodies were produced and used to study the LPS of standard and clinical strains. Although A-band antibodies did not agglutinate any of the serotype strains presently in the International Antigenic Typing Scheme, Western immunoblots revealed that 11 of the 17 serotype strains possessed A-band LPS. In a group of 250 clinical isolates from patients with cystic fibrosis, 170 (68%) had A-band LPS on the basis of agglutination tests, but in silver-stained gels all were shown to be deficient in O-antigen-containing B band. Investigation of serial isolates from a single patient revealed a pattern of antigenic variation. During the course of the infection, serotypeable isolates became nontypeable, and the O antigen was replaced with A band as the major LPS antigen. These results suggest that A-band LPS may be the major LPS antigen in nontypeable clinical isolates and a common antigen among other P. aeruginosa strains.

Analysis of a common-antigen lipopolysaccharide from Pseudomonas aeruginosa

Lipopolysaccharide isolated from Pseudomonas aeruginosa PAO1 (O5 serotype) was separated into two antigenically distinct fractions. A minor fraction, containing shorter polysaccharide chains, reacted with a monoclonal antibody to a P. aeruginosa common antigen but did not react with antibodies specific to O5-serotype lipopolysaccharide. In contrast, fractions containing long polysaccharide chains reacted only with the O5-specific monoclonal antibodies. The shorter, common-antigen fraction lacked phosphate and contained stoichiometric amounts of sulfate, and the fatty acid composition of this fraction was similar to that of the O-antigen-specific fraction. The lipid A derived from the serotype-specific lipopolysaccharide cross-reacted with monoclonal antibodies against lipid A from Escherichia coli, while the lipid A derived from the common antigen did not react. We propose that many serotypes of P. aeruginosa produce two chemically and antigenically distinct lipopolysaccharide molecules, one of which is a common antigen with a short polysaccharide and a unique core-lipid A structure.

Gas chromatographic determination of (phosphorylated) 2-keto-3-deoxyoctonic acid, heptoses and glucosamine in bacterial lipopolysaccharides after treatment with hydrofluoric acid, methanolysis and trifluoroacetylation

Quantification of phosphorylated sugar constituents of lipopolysaccharides has been performed by the following sequence: dephosphorylation by treatment with hydrofluoric acid, cleavage to monomeric constituents by methanolysis and analysis of the released sugars by capillary gas chromatography. Lipopolysaccharides of Salmonella minnesota Rd1P+, Bordetella pertussis NIH 114 and Vibrio cholerae, NAG and 95R strains, were used as model substances. Comparison of the chromatographic data obtained from hydrofluoric acid-treated and untreated lipopolysaccharide preparations indicated that all lipopolysaccharides examined contained one moiety of glucosamine bound to phosphate in a stable linkage. 2-Keto-3-deoxyoctonic acid appeared phosphorylated to a variable extent. Lipopolysaccharides of the two V. cholerae strains contained one moiety of fully phosphorylated 2-keto-3-deoxyoctonic acid, whereas in that of S. minnesota Rd1P+ only one of the three moieties was phosphorylated. Lipopolysaccharide of B. pertussis had one moiety of 2-keto-3-deoxyoctonic acid, ca. 70% phosphorylated. All four of the preparations examined contained L-glycero-D-manno-heptose in amounts varying from 2.6 to 5.2 moieties. In the lipopolysaccharides of B. pertussis and strain 95R of V. cholerae this sugar was unphosphorylated, whereas the two remaining strains contained one phosphorylated moiety of this sugar. Phosphorylated lipopolysaccharide constituents can be analysed by this approach on a 50-100 micrograms scale.

Chemical structure of the lipopolysaccharide of Haemophilus influenzae strain I-69 Rd-/b+. Description of a novel deep-rough chemotype

The chemical structure of the lipopolysaccharide of a deep-rough mutant (strain I-69 Rd-/b+) of Haemophilus influenzae was investigated. The hydrophilic backbone of lipid A was shown to consist of a beta-(1',6)-linked D-glucosamine disaccharide with phosphate groups at C-1 of the reducing D-glucosamine and at C-4' of the non-reducing one. Four molecules of (R)-3-hydroxytetradecanoic acid were found directly linked to the lipid A backbone, two by amide and two by ester linkage (positions 2,2' and 3,3', respectively). Laser-desorption mass spectrometry showed that both 3-hydroxytetradecanoic acids linked to the non-reducing glucosamine carry tetradecanoic acid at their 3-hydroxyl group, so that altogether six molecules of fatty acid are present in lipid A. The lipopolysaccharide was the first described to contain only one sugar unit linked to lipid A. This, sugar in accordance with a previous report [Zamze et al. (1987) Biochem. J. 245, 583-587], was shown to be a dOclA phosphate. The phosphate group was found at position 4, but the analytical procedures employed (permethylation and methanolysis followed by gas-liquid chromatography/mass spectrometry) also revealed dOclA 5-phosphate. Since a cyclic 4,5-phosphate could be ruled out by 31P-NMR, we conclude that, in this lipopolysaccharide, a mixture of dOclA 4- and 5-phosphate is present. By methylation analysis of the dephosphorylated, deacylated and reduced lipopolysaccharide the attachment site of the dOclA was assigned to position C-6' of the non-reducing glucosamine of lipid A. The anomeric linkages present in the lipopolysaccharide were assessed by 1H-NMR and 13C-NMR of deacylated lipopolysaccharide. The saccharide backbone of this Haemophilus influenzae lipopolysaccharide possesses the following structure: (Formula; see text)

Chemical and biological characterization of the lipopolysaccharide of the oral pathogen Wolinella recta ATCC 33238

To investigate the potential pathogenic mechanisms of the oral periodontopathogen Wolinella recta ATCC 33238, we have isolated its lipopolysaccharide (LPS) and determined the chemical composition and selected in vitro biological activities of the molecule. Sodium desoxycholate-polyacrylamide gel electrophoresis revealed the W. recta LPS to be an atypical smooth LPS with short O-antigenic side chains. Chemically the LPS consisted of 47.2% lipid A, 19.6% polysaccharide, 9.0% heptose, 8.5% hexosamine, 3.2% phosphate, and 0.6% 2-keto-3-deoxyoctanoate. The major fatty acids were hexadecanoic acid (25.0%), 3-OH tetradecanoic acid (23.8%), tetradecanoic acid (15.4%), 3-OH hexadecanoic acid (11.6%), and octadecenoic acid (10.9%). Rhamnose constituted 87.8% of the carbohydrates generally associated with the O antigen, with smaller amounts of glucose (5.5%), mannose (4.9%), and an unidentified sugar (1.9%). CD-1 and C3H/HeN macrophages (M phi) exposed to 1 microgram of W. recta LPS per ml released 6.0 and 10.5 ng of prostaglandin E per ml of supernatant, representing 625% and 1,306% of prostaglandin E release by the control (without LPS). Maximum prostaglandin E release occurred in CD-1 M phi exposed to 100 micrograms of LPS per ml and was equivalent to 1,542% of release by the control. Interleukin-1 (IL-1) activities in CD-1 and C3H/HeN M phi exposed to 1 micrograms of LPS per ml were 257% and 1,941% of activities in the control, respectively. Maximum IL-1 release in CD-1 M phi occurred in response to 50 micrograms of LPS per ml and represented a 927% increase over release in the control, while 100 micrograms LPS per ml stimulated maximum IL-1 release in C3H/HeN M phi that was greater than 5,000% of release by the control.

Heterogeneity of lipopolysaccharides from Pseudomonas aeruginosa: analysis of lipopolysaccharide chain length

Lipopolysaccharide (LPS) from smooth strains of Pseudomonas aeruginosa 503, PAZ1, PAO1715, PAO1716, and Z61 was fractionated by gel filtration chromatography. LPS samples from the first four strains, all PAO1 derivatives, separated into three major size populations, whereas LPS from strain Z61, a Pac K799/WT mutant strain, separated into two size populations. When column fractions were applied to sodium dodecyl sulfate-polyacrylamide gels in their order of elution, molecules of decreasing size were resolved, and the ladder of molecules with different-length O antigens formed a diagonal across the gel. The LPS from the PAO1 derivatives contained two distinct sets of bands, distinguished on the gels as two sets of diagonals. The set of bands with the faster mobility, the B bands, was found in column fractions comprising the three major amino sugar-containing peaks. In the sample from strain 503, a fourth minor peak which contained B bands was resolved. The slower-moving set of bands, the A bands, were recovered in a minor peak. LPS from strain Z61 contained only one set of bands, with the higher-molecular-weight molecules eluting from the column in a volume similar to that of the B bands of the PAO1 strains. Analysis of the fractions of LPS from all strains indicated that less than 8% of the LPS molecules had a long, attached O antigen. Analysis of the peak that contained mainly A bands indicated a lack of reactive amino sugar and phosphate, although heptose and 2-keto-3-deoxyoctulosonic acid were detected. Reaction of isolated fractions with monoclonal antibody specific for the PAO1 O-antigen side chain indicated that only the B bands from the PAO1 strains were antigenically reactive. The bands from strain Z61 showed no reactivity. The data suggest that the A and B bands from the PAO1 strains are antigenically distinct. We propose that PAO1 strains synthesize two types of molecules that are antigenically different.