Search

The polysaccharide capsule surrounding bacterial cell plays an important role in pathogenesis of infections caused by the opportunistic pathogen Acinetobacter baumannii by providing protection from external factors. The structures of the capsular polysaccharide (CPS) produced by A. baumannii isolates and the corresponding CPS biosynthesis gene clusters are highly diverse, although many of them are related. Many types of A. baumannii CPSs contain isomers of 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acid (DTNA). Three of these isomers, namely acinetaminic acid (l-glycero-l-altro isomer), 8-epiacinetaminic acid (d-glycero-l-altro isomer), and 8-epipseudaminic acid (d-glycero-l-manno isomer), have not been found so far in naturally occurring carbohydrates from other species. In A. baumannii CPSs, DTNAs carry N-acyl substituents at positions 5 and 7; in some CPSs, both N-acetyl and N-(3-hydroxybutanoyl) groups are present. Remarkably, pseudaminic acid carries the (R)-isomer and legionaminic acid carries the (S)-isomer of the 3-hydroxybutanoyl group. The review addresses the structure and genetics of biosynthesis of A. baumannii CPSs containing di-N-acyl derivatives of DTNA. [ABSTRACT FROM AUTHOR]

Abstract Escherichia coli F17 isolated from horse feces was studied in respect to the O antigen (O polysaccharide) structure and genetics. The lipopolysaccharide was isolated by phenol-water extraction of bacterial cells and cleaved by mild acid hydrolysis to yield the O polysaccharide, which was studied by sugar analysis and selective solvolysis with CF 3 CO 2 H along with one- and two-dimensional 1H and 13C NMR spectroscopy. The O polysaccharide was found to have a branched pentasaccharide repeat (O-unit) containing one residue each of d -galactose, d -mannose, l -rhamnose, d -glucuronic acid, and N -acetyl- d -glucosamine; about 2/3 units bear a side-chain glucose residue. To our knowledge, the F17 O-polysaccharide structure established is unique among known bacterial polysaccharide structures. The O-antigen gene cluster of E. coli F17 between the conserved genes galF and gnd was sequenced and found to be 99% identical to that of E. coli 102,755 assigned to a novel OgN8 genotype (A. Iguchi, S. Iyoda, K. Seto, H. Nishii, M. Ohnishi, H. Mekata, Y. Ogura, T. Hayashi, Front. Microbiol. 7 (2016) 765). Genes in the cluster were annotated taking into account the F17 O-polysaccharide structure. The data obtained confirm that E. coli F17 and E. coli strains belonging to the OgN8 genotype can be considered as a candidate to a new E. coli O-serogroup. The O antigen of this novel type was demonstrated to make for an effective shield protecting the intimate outer membrane surface of bacteria from direct interaction with bacteriophages. [ABSTRACT FROM AUTHOR]

In 2017, we reported a new database on glycosyltransferase (GT) activities, CSDB_GT (http://csdb.glycoscience.ru/gt.html), which was built at the platform of the Carbohydrate Structure Database (CSDB, http://csdb.glycoscience.ru/database/index.html) and contained data on experimentally confirmed GT activities from Arabidopsis thaliana. All entries in CSDB_GT are curated manually upon the analysis of scientific publications, and the key features of the database are accurate structural, genetic, protein and bibliographic references and close-to-complete coverage on experimentally proven GT activities in selected species. In 2018, CSDB_GT was supplemented with data on Escherichia coli GT activities. Now it contains ca. 800 entries on E. coli GTs, including ca. 550 entries with functions predicted in silico. This information was extracted from research papers published up to the year 2018 or was obtained by the authors' efforts on GT annotation. Thus, CSDB_GT was extended to provide not only experimentally confirmed GT activities, but also those predicted on the basis of gene or protein sequence homology that could carry valuable information. Accordingly, a new confirmation status—predicted in silico —was introduced. In addition, the coverage on A. thaliana was extended up to ca. 900 entries, all of which had experimental confirmation. Currently, CSDB_GT provides close-to-complete coverage on experimentally confirmed GT activities from A. thaliana and E. coli presented up to the year 2018. [ABSTRACT FROM AUTHOR]

Fine structure of the O-polysaccharide chain of the lipopolysaccharide (O-antigen) defines the serospecificity of bacterial cells, which is the basis for O-serotyping of medically and agriculturally important gram-negative bacteria including Escherichia coli . In order to obtain the O-polysaccharide for structural analysis, the lipopolysaccharide was isolated from cells of E. coli O84a by phenol/water extraction and degraded with mild acid. However, the O-polysaccharide was cleaved at a highly acid-labile β- l -fucopyranosyl phosphate (β- l -Fuc p -1- P ) linkage to give mainly a pentasaccharide that corresponded to the O-polysaccharide repeat. Therefore, the lipopolysaccharide and the pentasaccharide as well as their O-deacylated derivatives were studied using sugar analysis, NMR spectroscopy, and (for oligosaccharides) ESI HR MS, and the O84-polysaccharide structure was established. The O-polysaccharide is distinguished by the presence of β- l -Fuc p -1- P and randomly di-O-acetylated 6-deoxy- d -talose, which are found for the first time in natural carbohydrates. The gene cluster for the O84-antigen biosynthesis was analysed and its content was found to be consistent with the O-polysaccharide structure. [ABSTRACT FROM AUTHOR]

The O polysaccharide of the lipopolysaccharide (O antigen) of Gram-negative bacteria often serves as a receptor for bacteriophages that can make the phage dependent on a given O-antigen type, thus supporting the concept of the adaptive significance of the O-antigen variability in bacteria. The O-antigen layer also modulates interactions of many bacteriophages with their hosts, limiting the access of the viruses to other cell surface receptors. Here we report variations of O-antigen synthesis and structure in an environmental Escherichia coli isolate, 4s, obtained from horse feces, and its mutants selected for resistance to bacteriophage G7C, isolated from the same fecal sample. The 4s O antigen was found to be serologically, structurally, and genetically related to the O antigen of E. coli O22, differing only in side-chain α-D-glucosylation in the former, mediated by a gtr locus on the chromosome. Spontaneous mutations of E. coli 4s occurring with an unusually high frequency affected either O-antigen synthesis or O-acetylation due to the inactivation of the gene encoding the putative glycosyltransferase WclH or the putative acetyltransferase WclK, respectively, by the insertion of IS1-like elements. These mutations induced resistance to bacteriophage G7C and also modified interactions of E. coli 4s with several other bacteriophages conferring either resistance or sensitivity to the host. These findings suggest that O-antigen synthesis and O-acetylation can both ensure the specific recognition of the O-antigen receptor following infection by some phages and provide protection of the host cells against attack by other phages. [ABSTRACT FROM AUTHOR]

Background O-antigen (O-polysaccharide) of the lipopolysaccharide is a highly variable cell component of the outer membrane in Shigella flexneri. It defines the serospecificity and plays an important role in the pathogenesis of shigellosis. There are two distinct O-antigen forms for the 19 serotypes of S. flexneri: one for serotypes 1-5, X, Y, 7 (and their subtypes), and the other for serotype 6. Although having different basal O-polysaccharide structures, the two forms share a common disaccharide fragment [→2)-α-L-RhapIII-(1 → 2)-α-L-RhapII]. In serotype 6 and some non-6 serotypes, RhaIII is O-acetylated at position either 3 or 4 (3/4-Oacetylation), conferring to the hosts a novel antigenic determinant named O-factor 9. An acyltransferase gene (oacB) responsible for this modification has been identified in serotypes 1a, 1b, 2a, 5a, and Y, but not in serotype 6. Results Using genetic, serological, and chemical approaches, another acyltransferase gene named oacC was demonstrated to be responsible for the 3/4-O-acetylation on RhaIII in the O-antigen of S. flexneri serotype 6. Inactivation of the oacC gene resulted in the loss of the 3/4-Oacetyltion, and the cloned oacC gene restored this modification upon transformation. In accordance with the similarity in the acceptor substrate structure and high sequence homology (72% identity) between oacC and oacB, oacC has the interchangeable function with the oacB gene in mediation of the 3/4-O-acetylation. The oacC gene is located in a prophage on the chromosome and presented in all 77 serotype 6 strains tested. Conclusions Identification and functional characterization of the O-acetyltransferase encoding gene, oacC, shows that it is involved in O-antigen modification by 3/4-O-acetylation on RhaIII specific to serotype 6. [ABSTRACT FROM AUTHOR]

Shigella flexneri O-antigen is an important and highly variable cell component presented on the outer leaflet of the outer membrane. Most Shigella flexneri bacteria share an O-antigen backbone composed of →2)-α-L-RhapIII-(1→2)- α-L-RhapII-(1→3)-α-L- RhapI-(1→3)-β-D-GlcpNAc-(1→ repeats, which can be modified by adding various chemical groups to different sugars, giving rise to diverse O-antigen structures and, correspondingly, to various serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on RhaI or/and RhaIII, and phosphorylation with phosphoethanolamine on RhaII or/ and RhaIII. Recently, a new O-antigen modification, namely, O-acetylation at position 6 of N-acetylglucosamine (GlcNAc), has been identified in S. flexneri serotypes 2a, 3a, Y, and Yv. In this study, the genetic basis of the 6-O-acetylation of GlcNAc in S. flexneri was elucidated. An O-acyltransferase gene designated oacD was found to be responsible for this modification. The oacD gene is carried on serotype-converting bacteriophage SflI, which is integrated into the host chromosome by lysogeny to form a prophage responsible for the evolvement of serotype 2 of S. flexneri. The OacD-mediated 6-O-acetylation also occurs in some other S. flexneri serotypes that carry a cryptic SflI prophage with a dysfunctional gtr locus for type II glucosylation. The 6-Oacetylation on GlcNAc confers to the host a novel O-antigen epitope, provisionally named O-factor 10. These findings enhance our understanding of the mechanisms of the O-antigen variation and enable further studies to understand the contribution of the O-acetylation to the antigenicity and pathogenicity of S. flexneri. [ABSTRACT FROM AUTHOR]

O antigen (O polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of Gram-negative bacteria. Most O antigens of Shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-L-RhapIII-(1→2)-α-L-RhapII-(1→3)-α-L-RhapI-(1→3)-β-D-GlcpNAc-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on RhaI, and phosphorylation with phosphoethanolamine on RhaII or/and RhaIII. Recently, two new O-antigen modifications, namely, O-acetylation at position 3 or 4 of RhaIII and position 6 of GlcNAc, have been identified in several S. flexneri serotypes. In this work, the genetic basis for the 3/4-O-acetylation on RhaIII was elucidated. Bioinformatic analysis of the genome of S. flexneri serotype 2a strain Sf301, which carries 3/4-O-acetylation on RhaIII, revealed an O-acyltransferase gene designated oacB. Genetic studies combined with O-antigen structure analysis demonstrated that this gene is responsible for the 3/4-O-acetylation in serotypes 1a, 1b, 2a, 5a, and Y but not serotype 6, which has a different O-antigen backbone structure. The oacB gene is carried by a transposon-like structure located in the proA-adrA region on the chromosome, which represents a novel mechanism of mobilization of O-antigen modification factors in S. flexneri. These findings enhance our knowledge of S. flexneri O-antigen modifications and shed light on the origin of new O-antigen variants. [ABSTRACT FROM AUTHOR]

The O-antigens of all Shigella flexneri serotypes, except serotype 6, share a linear tetrasaccharide repeat composed of one N-acetylglucosamine and three l-rhamnose residues, and differences between the serotypes are due to modification of various monosaccharide residues with glucosyl and/or O-acetyl and/or phosphoethanolamine (PEtN) groups. Plasmid-borne opt (formerly lpt-O) gene encoding a PEtN transferase which modifies the O-antigens of S. flexneri serotype X, 4a and Y strains and converts the hosts into MASF IV-1 (E1037) positive “variant” (v) Xv, 4av and Yv serotypes, respectively. In this study, we showed that the opt-carrying plasmid pSFxv_2 can transform strains of all S. flexneri serotypes (1–6) to confer them with the MASF IV-1 epitope recognized by monoclonal antibody MASF IV-1 and typing antiserum IV. The transformants possessed modified O-antigens with a PEtN group(s) at position 3 of one or two rhamnose residues. In some serotypes, the PEtN modification competed or/and interfered with glucosylation and O-acetylation at the same or its neighboring sugar residue. We also showed that the plasmid pSFxv_2 is mobilizable to other S. flexneri strains by conjugation. Although pSFxv_2-harboring S. flexneri strains found in clinical infections are restricted to serotypes Xv, 4av, Yv and, possibly, 6v, our results demonstrate a high potential of dissemination of this plasmid in S. flexneri and emergence of new S. flexneri serotypes. [ABSTRACT FROM AUTHOR]

This review covers the structures and genetics of the 46 O antigens of Salmonella, a major pathogen of humans and domestic animals. The variation in structures underpins the serological specificity of the 46 recognized serogroups. The O antigen is important for the full function and virulence of many bacteria, and the considerable diversity of O antigens can confer selective advantage. Salmonella O antigens can be divided into two major groups: those which have N-acetylglucosamine ( Glc NAc) or N-acetylgalactosamine ( Gal NAc) and those which have galactose ( Gal) as the first sugar in the O unit. In recent years, we have determined 21 chemical structures and sequenced 28 gene clusters for Glc NAc-/ Gal NAc-initiated O antigens, thus completing the structure and DNA sequence data for the 46 Salmonella O antigens. The structures and gene clusters of the Glc NAc-/ Gal NAc-initiated O antigens were found to be highly diverse, and 24 of them were found to be identical or closely related to Escherichia coli O antigens. Sequence comparisons indicate that all or most of the shared gene clusters were probably present in the common ancestor, although alternative explanations are also possible. In contrast, the better-known eight Gal-initiated O antigens are closely related both in structures and gene cluster sequences. [ABSTRACT FROM AUTHOR]

Shigella flexneri is the major human pathogen causing shigellosis. O-antigens of all S. flexneri serotypes (except for serotype 6) share the →2)-α-l-RhapIII-(1 → 2)-α-l-RhapII-(1 → 3)-α-l-RhapI-(1 → 3)-β-d-GlcpNAc-(1→ basic O-unit, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation at various positions. Recently, in serotype X and 4a variants called Xv and 4av, respectively, O-antigen modification with phosphoethanolamine (PEtN) has been identified, which is encoded by a plasmid-borne gene (lpt-O) for a PEtN-transferase and confers the monoclonal antibody IV-1(MASF IV-1) determinant to the bacteria. In this study, we elucidated the O-antigen structure of serotype Yv, another MASF IV-1-positive novel variant of S. flexneri. The serotype Yv O-antigen has the same basic carbohydrate backbone structure as that of the “classical” serotype Y, but differs in the presence of PEtN at position 3 of RhaIII (major) or both RhaII and RhaIII (minor). This pattern is similar to that of serotype 4av, but different from the pattern of serotype Xv, which is characterized by major PEtN modification on RhaII. In serotype Yv, mono- and bisphosphorylated O-units generate a block-copolymeric structure, the former being partially O-acetylated at position 6 of GlcNAc and the latter lacking O-acetylation. Functional analysis revealed a correlation between the serotype-specific PEtN modification pattern and the lpt-O variation in different serotypes: lpt-ORII in serotype Xv is better tuned for phosphorylation of RhaII and lpt-ORIII in serotypes Yv and 4av for phosphorylation of RhaIII. These data enhance our knowledge of S. flexneri serotype conversion mechanisms and help to understand the biosynthesis process of the new O-antigen variants. [ABSTRACT FROM AUTHOR]

We experimentally identified the activities of six predicted heptosyltransferases in Actinobacillus pleuropneumoniae genome serotype 5b strain L20 and serotype 3 strain JL03. The initial identification was based on a bioinformatic analysis of the amino acid similarity between these putative heptosyltrasferases with others of known function from enteric bacteria and Aeromonas. The putative functions of all the Actinobacillus pleuropneumoniae heptosyltrasferases were determined by using surrogate LPS acceptor molecules from well-defined A. hydrophyla AH-3 and A. salmonicida A450 mutants. Our results show that heptosyltransferases APL_0981 and APJL_1001 are responsible for the transfer of the terminal outer core D-glycero-Dmanno- heptose (D,D-Hep) residue although they are not currently included in the CAZY glycosyltransferase 9 family. The WahF heptosyltransferase group signature sequence [S(T/S)(GA)XXH] differs from the heptosyltransferases consensus signature sequence [D(TS)(GA)XXH], because of the substitution of D261 for S261, being unique. [ABSTRACT FROM AUTHOR]

Shigella flexneri is the major pathogen causing bacillary dysentery in developing countries. S. flexneri is divided into at least 16 serotypes based on the combination of antigenic determinants present in the O-antigen. All the serotypes (except for serotype 6) share a basic O-unit containing one N-acetyl-D-glucosamine and three L-rhamnose residues, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation. Serotype Xv is a newly emerged and the most prevalent serotype in China, which can agglutinate with both MASF IV-1 and 7,8 monoclonal antibodies. The factor responsible for the presence of MASF IV-1 (E1037) epitope has not yet been identified. In this study, we analyzed the LPS structure of serotype Xv strains and found that the MASF IV-1 positive phenotype depends on an O-antigen modification with a phosphoethanolamine (PEtN) group attached at position 3 of one of the rhamnose residues. A plasmid carried gene, lpt-O (LPS phosphoethanolamine transferase for O-antigen), mediates the addition of PEtN for serotype Xv and other MASF IV-1 positive strains. These findings reveal a novel serotype conversion mechanism in S. flexneri and show the necessity of further extension of the serotype classification scheme recognizing the MASF IV-1 positive strains as distinctive subtypes. [ABSTRACT FROM AUTHOR]

Bacteria Shigella, the cause of shigellosis, evolved from the intestinal bacteria Escherichia coli. Based on structurally diverse O-specific polysaccharide chains of the lipopolysaccharides (LPSs; O-antigens), three from four Shigella species are subdivided into multiple serotypes. The central oligosaccharide of the LPS called core is usually conserved within genus but five core types called R1–R4 and K-12 have been recognized in E. coli. Structural data on the Shigella core are limited to S. sonnei, S. flexneri and one S. dysenteriae strain, which all share E. coli core types. In this work, we elucidated the core structure in 14 reference strains of S. dysenteriae and S. boydii. Core oligosaccharides were obtained by mild acid hydrolysis of the LPSs and studied using sugar analysis, high-resolution mass spectrometry and two-dimensional NMR spectroscopy. The R1, R3 and R4 E. coli core types were identified in 8, 3 and 2 Shigella strains, respectively. A novel core variant found in S. boydii type 16 differs from the R3 core in the lack of GlcNAc and the presence of a d-glycero-d-manno-heptose disaccharide extension. In addition, the structure of an oligosaccharide consisting of the core and one O-antigen repeat was determined in S. dysenteriae type 8. A clear correlation of the core type was observed with genetic grouping of Shigella strains but not with their traditional division to four species. This finding supports a notion on the existing Shigella species as invalid taxa and a suggestion of multiple independent origins of Shigella from E. coli clones. [ABSTRACT FROM PUBLISHER]

Recent data on the natural occurrence, chemistry, and biochemistry of C8 and C9 aldulosonic acids (3-deoxy-D-manno-oct-2-ulosonic acid, sialic acids, N-acyl derivatives of 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acids, and some others) as well as on the structures and biological significance of bacterial glycans containing these higher acidic monosaccharides are summarized. [Copyright &y& Elsevier]

This review is devoted to structural and serological characteristics of the O-antigens (O-polysaccharides) of the lipopolysaccharides of various Proteus species, which provide the basis for classifying Proteus strains to Oserogroups. The antigenic relationships of Proteus strains within and beyond the genus as well as their O-antigenrelated bioactivities are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: A polysaccharide was isolated by GPC after mild acid treatment of the lipopolysaccharide of Vibrio vulnificus CECT4602 and found to contain l-Rha, d-GlcpNAc and 2-acetamido-2,3,6-trideoxy-3-(3-hydroxybutanoylamino)-l-mannose (l-RhaNAc3NHb). GLC analysis of the trifluoroacetylated (S)-2-octyl esters derived by full acid hydrolysis of the polysaccharide showed that ∼80% of the 3-hydroxybutanoic acid has the S configuration and ∼20% the R configuration. The following structure of the polysaccharide was established by 1H and 13C NMR spectroscopies, including 2D ROESY and 1H/13C HMBC experiments: ▪ [Copyright &y& Elsevier]

Lipopolysaccharide (LPS), localized in the outer leaflet of the outer membrane, serves as the major surface component of the Gram-negative bacterial cell envelope responsible for the activation of the host's innate immune system. Variations of the LPS structure utilized by Gram-negative bacteria promote survival by providing resistance to components of the innate immune system and preventing recognition by TLR4. This review summarizes studies of the biosynthesis of Yersinia pseudotuberculosis complex LPSs, and the roles of their structural components in molecular mechanisms of yersiniae pathogenesis and immunogenesis. [ABSTRACT FROM AUTHOR]

This review covers the O antigens of the 46 serotypes of Shigella, but those of most Shigella flexneri are variants of one basic structure, leaving 34 Shigella distinct O antigens to review, together with their gene clusters. Several of the structures and gene clusters are reported for the first time and this is the first such group for which structures and DNA sequences have been determined for all O antigens. Shigella strains are in effect Escherichia coli with a specific mode of pathogenicity, and 18 of the 34 O antigens are also found in traditional E. coli. Three are very similar to E. coli O antigens and 13 are unique to Shigella strains. The O antigen of Shigella sonnei is quite atypical for E. coli and is thought to have transferred from Plesiomonas. The other 12 O antigens unique to Shigella strains have structures that are typical of E. coli, but there are considerably more anomalies in their gene clusters, probably reflecting recent modification of the structures. Having the complete set of structures and genes opens the way for experimental studies on the role of this diversity in pathogenicity. [ABSTRACT FROM AUTHOR]

The review is devoted to recent progress in the structural elucidation of the lipopolysaccharide of the bacterium Pseudomonas aeruginosa, including O-antigen biological repeats, core oligosaccharide, and lipid A. Data on biosynthesis, genetics and serology of the lipopolysaccharide isolated from various P. aeruginosa O-serogroups are discussed in relation to the chemical structures. [ABSTRACT FROM AUTHOR]

Data on the structure and temperature-dependent variations of the lipopolysaccharide (LPS) of Yersinia pestis are summarized and compared with data of other enteric bacteria, including other Yersinia spp. A correlation between the LPS structure and properties of the LPS and bacterial cultures as well as the LPS biosynthesis control are briefly discussed. [ABSTRACT FROM AUTHOR]

Highly phosphorylated core oligosaccharides and those substituted with one O-antigen repeating unit were obtained by mild acid degradation or strong alkaline hydrolysis of lipopolysaccharide samples from 23 reference strains representing all Pseudomonas aeruginosa O-serogroups. Studies by high-resolution electrospray ionization mass spectrometry and two-dimensional NMR spectroscopy revealed both conserved and variable structural features of the lipopolysaccharides of various O-serogroups. The upstream terminal saccharide of the O-antigen, which contributes most to the immunospecificity of the bacteria, was defined in 11 from a total of 13 O-serogroups. The data obtained link together the known biosynthesis pathways, genetics and serology of the P. aeruginosa lipopolysaccharide. [ABSTRACT FROM AUTHOR]

Abstract: Following a report of variations in the lipopolysaccharide (LPS) structure of Yersinia pestis at mammalian (37°C) and flea (25°C) temperatures, a number of changes to the LPS structure were observed when the bacterium was cultivated at a temperature of winter-hibernating rodents (6°C). In addition to one of the known Y. pestis LPS types, LPS of a new type was isolated from Y. pestis KM218 grown at 6°C. The core of the latter differs in: (i) replacement of terminal galactose with terminal d-glycero-d-manno-heptose; (ii) phosphorylation of terminal oct-2-ulosonic acid with phosphoethanolamine; (iii) a lower content of GlcNAc, and; (iv) the absence of glycine; lipid A differs in the lack of any 4-amino-4-deoxyarabinose and presumably partial (di)oxygenation of a fatty acid(s). The data obtained suggest that cold temperature switches on an alternative mechanism of control of the synthesis of Y. pestis LPS. [Copyright &y& Elsevier]

Yersinia pestis spread throughout the Americas in the early 20th century, and it occurs predominantly as a single clone within this part of the world. However, within Eurasia and parts of Africa there is significant diversity among Y. pestis strains, which can be classified into different biovars (bv.) and/or subspecies (ssp.), with by. orientalis/ssp. pestis most closely related to the American clone. To determine one aspect of the relatedness of these different Y. penis isolates, the structure of the lipopolysaccharide (LPS) of four wild-type and one LPS-mutant Eurasian/African strains of Y. penis was determined, evaluating effects of growth at mammalian (37 °C) or flea (25 °C) temperatures on the structure and composition of the core oligosaccharide and lipid A. In the wild-type clones of ssp. penis, a single major core glycoform was synthesized at 37 °C whereas multiple core oligosaccharide glycoforms were produced at 25 °C. Structural differences occurred primarily in the terminal monosaccharides. Only tetraacyl lipid A was made at 37 °C, whereas at 25 °C additional pentaacyl and hex aacyl lipid A structures were produced. 4-Aniino-4-deoxyarabinose levels in lipid A increased with lower growth temperatures or when bacteria were cultured in the presence of polymyxin B. In Y. penis ssp. caucasica, the LPS core lacked D-glycero-D-Pnanno-heptose and the content of 4-amino-4-deoxyarabinose showed no dependence on growth temperature, whereas the degree of acylation of the lipid A and the structure of the oligosaccharide core were temperature dependent. A spontaneous deep-rough LPS mutant strain possessed only a disaccharide core and a slightly variant lipid A. The diversity and differences in the structure of the Y. pestis LPS suggest important contributions of these variations to the pathogenesis of this organism, potenfi ally related to innate and acquired immune recognition of Y. pestis and epidemiologic means to detect, classify, control and respond to Y. penis infections. [ABSTRACT FROM AUTHOR]

A rough strain of Aeromonas hydrophila, AH-901, has an R-type lipopolysaccharide with the complete core. The following core structure was established by chemical degradations followed by sugar and methylation analyses along with ESIMS and NMR spectroscopy:where d-α-d-Hep and l-α-d-Hep stand for d-glycero- and l-glycero-α-d-manno-heptose, respectively; Kdo stands for 3-deoxy-d-manno-oct-2-ulosonic acid; all monosaccharides are in the pyranose form; the degree of substitution with β-d-Gal is ∼50%. Lipid A of the lipopolysaccharide has a 1,4′-bisphosphorylated β-d-GlcN-(1 → 6)-α-d-GlcN disaccharide backbone with both phosphate groups substituted with 4-amino-4-deoxyarabinose residues. [Copyright &y& Elsevier]

The O-polysaccharide of Aeromonas hydrophila O:34 was obtained by mild-acid degradation of the lipopolysaccharide and studied by chemical methods and NMR spectroscopy before and after O-deacetylation. The polysaccharide was found to contain d-Man, d-GalNAc and 6-deoxy-l-talose (l-6dTal), and the following structure of the tetrasaccharide repeating unit was established:where 6dTalI is O-acetylated stoichiometrically at position-2 and 6dTalII carries no, one or two O-acetyl groups at any positions. [Copyright &y& Elsevier]

Lipopolysaccharide (LPS) expressed by isolates of Pseudomonas aeruginosa from cystic fibrosis patients lacks the O-polysaccharide chain but the degree to which the rest of the molecule changes has not been determined. We analyzed, for the first time, the core structure of an LPS from a rough, cystic fibrosis isolate of P. aeruginosa. The products of mild acid hydrolysis and strong alkaline degradation of the LPS were studied by ESI MS, MALDI MS, and NMR spectroscopy. The following structure was determined for the highest-phosphorylated core-lipid A backbone oligosaccharide isolated after alkaline deacylation of the LPS: &figf7; where Kdo and Hep are 3-deoxy-d-manno-octulosonic acid and l-glycero-d-manno-heptose, respectively; all sugars are in the pyranose form and have the d configuration unless stated otherwise. The outer core region occurs as two isomeric glycoforms differing in the position of rhamnose (Rha). The inner core region carries four phosphorylation sites at two Hep residues, HepI being predominantly bisphosphorylated and HepII monophosphorylated. In the intact LPS, both Hep residues carry monophosphate and diphosphate groups in nonstoichiometric quantities, GalN is N-acylated by an l-alanyl group, HepII is 7-O-carbamoylated, and the outer core region is nonstoichiometrically O-acetylated at four sites. Therefore, the switch to the LPS-rough phenotype in cystic fibrosis isolates of P. aeruginosa is not accompanied by losses of core monosaccharide, phosphate or acyl components. The exact positions of the O-acetyl groups and the role of the previously undescribed O-acetylation in the LPS core of P. aeruginosa remain to be determined. [ABSTRACT FROM AUTHOR]

Examines the structure of an atypical O-chain polysaccharide (PS) of Helicobacter pylori. Composition of the liberated atypical PS; Presence of a trisaccharide repeating unit in the D1, D3, and D6 PS strains; Occurrence of gamma-gauche interaction in the residues; Rationale for the production of a differing surface PS.

Studies the structure of a 2-aminoethyl phosphate-containing O-specific polysaccharide of Proteus penneri 8 from the serogroup O67. Process used for obtaining bacterial strains for the experiment; Method used for the preparation of O-antiserum and serological assays; Structure of the polysaccharide observed by chemical and nuclear magnetic resonance spectroscopic studies.

Examines the O polysaccharides in the lipopolysaccharides (LPS) of the Pseudomonas syringae serogroup 01 strains. Improvement of the serological classification scheme of P. syringae; Presence of strains in the serogroup 01 of several pathovars; Possible role of LPS as a phylogenetic marker.

Characterizes a locus responsible for O acetylation of the O polysaccharide of Legionella pneumophila serogroup 1 lipopolysaccharide. Complementation of strain CS332; Localization and nucleotide sequence of lag-1 gene; Distribution of the lag-1 locus.

Investigates the structure on lipopolysaccharides of serologically non-typable strains of Helicobacter pylori. Liberation of the carbohydrate portions; Development of gastric cancer; Relevance of Lewis antigen.

The O polysaccharide (OPS) of the lipopolysaccharide of Pseudomonas syringae pv. coriandricola GSPB 2028 (NCPPB 3780, W-43) was studied by Smith degradation and 1H-NMR and 13C-NMR spectroscopy, including two-dimensional COSY, TOCSY, NOESY, and H-detected 1H,13C heteronuclear multiple-quantum coherence (HMQC) experiments. The OPS was shown to consist of pentasaccharide O repeats of two types both containing four L-rhamnose and one 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc) residue. Structure 1 of the major O repeat which had been established earlier [Das, S., Ramm, M., Kochanowski, H. & Basu, S. (1994) J. Bacteriol. 176, 6550-6557], was confirmed by our data, and a new structure 2 was elucidated for the minor O repeat and found to differ from the structure 1 only in the position of substitution of one of the rhamnose residues in the main chain. α-D-Fucp3NAc 1 ↓ 2 ←2)-α-L-Rhap-(1←2)-α-L-Rhap-(1←3)-α-L-Rhap-(1←3)-α-L-Rhap-(1← 1 α-D-Fucp3NAc 1 ↓ 2 ←3)-α-L-Rhap-(1←2)-α-L-Rhap-(1←3)-α-L-Rhap-(1←3)-α-L-Rhap-(1← 2 A role of structural and immunochemical features of the LPS for defining the taxonomical position of the bacterium studied is discussed. [ABSTRACT FROM AUTHOR]

O polysaccharides (OPS) of the lipopolysaccharides (LPS) of Pseudomonas syringae pathovar tomato GSPB 483 and pathovar maculicola IMV 381 were studied by 1H-NMR and 13C-NMR spectroscopy, including two-dimensional COSY, rotating-frame NOE spectroscopy (ROESY), and H-detected 1H,13C heteronuclear multiple-quantum coherence (HMQC) experiments. The OPS from both strains were shown to be chemically identical. Two structurally different types of repeating units (O repeats 1 and 2) were elucidated in each OPS. The minor O repeat is a pentasaccharide having the structure 2. The same structure has been reported earlier for some other OPS of P. syringae. The major O repeat is a hexasaccharide with the novel structure 1 which is distinguished from 2 by the presence of the second lateral residue of 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc) and by a different position of substitution of one of the L-rhamnose (Rha) residues in the backbone. α-D-Fucp3NAc α-D-Fucp3NAc 1 1 ↓ ↓ 3 3 ←2)-α-L-Rhap-(1←2)-α-L-Rhap-(1←3)-α-L-Rhap-(1←3)-α-L-Rhap-(1← 1 α-D-Fucp3NAc 1 ↓ 3 ←2)-α-L-Rhap-(1←3)-α-L-Rhap-(1←3)-α-L-Rhap-(1←3)-α-L-Rhap-(1← 2 Structural and serological diversity of OPS of strains belonging to P. syringae pv. tomato and pv. maculicola and phylogenetic relatedness of the strains are discussed. [ABSTRACT FROM AUTHOR]

An R-type lipopolysaccharide (LPS) from Erwinia carotovora strain FERM P-7576 was studied after strong alkaline degradation and mild acid hydrolysis. The resulting products were analyzed by fast-atom bombardment mass spectrometry, one- and two-dimensional 1H and 13C NMR spectroscopy, dephosphorylation and methylation analysis. The following structure was proposed for the core region of the LPS: [This symbol cannot be presented in ASCII format] where Hep is L-glycero-D-manno-heptose and Kdo is 3-deoxy-D-manno-octulosonic acid. Some LPS species lack the β-D GAlp residue or the β-D-Galp-(1→7)-α-Hepp disaccharide. With the known structures of lipid A [Fukuoka, S., Kamishima, H., Nagawa. Y., Nakanishi, H., Ishikawa, K., Niwa, Y., Tamiya, E. & Karube, I. (1992) Arch. Microbiol. 157, 311–318] and the core moiety, the complete LPS structure was established and confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry of the native and O-deacylated LPS. [ABSTRACT FROM AUTHOR]

Reports on a Vibrio cholerae O139 strain, MO10-T4, lacking capsular polysaccharide, which produces a short-chain lipopolysaccharide (LPS) similar to enterobacterial SR strains. Study of the strain by acidic and alkaline degradation, dephosphorylation, sugar and methylation analysis; Structure proposed for the core region of the LPS; Presence of an O-acetyl group on a secondary position; Additional putative fructose residue contained by some LPS species.

The O-specific polysaccharide of an Aeromonas trota strain was isolated by hydrolysis of the lipopolysaccharide at pH 4.5 followed by gel-permeation chromatography and found to consist of hexasaccharide repeating units containing D-galactose, L-rhamnose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-galactose in the ratios 1:1:2:1:1. Partial hydrolysis of the polysaccharide with 48% hydrofluoric acid resulted in selective removal of colitose to give a modified polysaccharide containing the other four sugar constituents. On the basis of methylation analysis and NMR spectroscopic studies of the initial and modified, colitose-free polysaccharide, it was concluded that the repeating unit of the O-specific polysaccharide has the following structure [This text cannot be captured in ASCII.text] The known cross-reactivity between the strain studied and Vibrio cholerae O139 Bengal is substantiated by the presence of a common colitose-containing epitope shared by the O-specific polysaccharide of A. trota and the capsular polysaccharide of V. cholerae, which is thought to carry determinants of O-specificity. [ABSTRACT FROM AUTHOR]

On the basis of sugar analysis and NMR spectroscopy, including selective spin-decoupling, one-dimensional NOE, two-dimensional homonuclear and 13C,¹H-heteronuclear correlation spectroscopy, the following structure of the acidic O-specific polysaccharide of Proteus mirabilis O43 was established: →4)-α-D-GalpA-(1→3)-α-D-GalpA-(1→3)-α-D-Gl cpNAc-(1→4)-α - D-Glcp-(1→, where GalA is galacturonic acid and Galp is galactopyranose. No serological cross-reactivity was observed between lipopolysaccharides of P. mirabilis O43 and other studied Proteus strains, except for P. mirabilis O10. The O-specific polysaccharide of P. mirabilis O43 was serologically active in precipitation and inhibition tests but the activity was lost after periodate oxidation. These data suggest that the O43 specificity is determined by a wide epitope with the immunodominant role of 4-substituted D-Glc or/and D-GalA, which are destroyed by periodate oxidation. [ABSTRACT FROM AUTHOR]

The capsular polysaccharide (CPS) of Vibrio cholerae O139 synonym Bengal, which is thought to carry determinants of O-specificity, was isolated by phenol/water extraction followed by delipidation of the contaminating lipopolysaccharide at pH 4.2 and gel-permeation chromatography. The CPS contained D-galactose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2,6-dideoxy-D-glucose (N-acetyl-D-quinovosamine, D-QuiNAc), D-galacturonic acid (D-GalA), and phosphate. The CPS was studied by NMR spectroscopy, methylation analysis, and selective degradations, including partial acid hydrolysis at pH 3.1 and dephosphorylation with aqueous 48% hydrofluoric acid, which both resulted in complete cleavage of Col. It was concluded that the CPS is built up of hexasaccharide repeating units containing inter alia D-galactose 4,6-cyclophosphate and having the following structure [This structure can not be represented in to (ASCII.txt)] These data basically confirm the structure of the V. cholerae CPS proposed on the basis of an NMR study [L. M. Preston et al. (1995) J. Bacteriol. 177, 835-838] and specify exactly the absolute configurations of the constituent monosaccharides and the position of the cyclic phosphate. [ABSTRACT FROM AUTHOR]

Structural and immunochemical studies have been performed on the O-specific antigens of two serologically related types of Pseudomonas aeruginosa O:2a,b and O:2a,c (Lanyi's classification). The O-specific polysaccharide chains of the two serotypes were shown to be acidic polysaccharides composed of repeating trisaccharide units consisting of L-rhamnose, N-acetyl-D-quinovosamine and N-acetyl-L-galactosaminuronic acid residues. Based on 1H and 13C nuclear magnetic resonance spectroscopy, data of methylation analysis and selective solvolysis with hydrogen fluoride, the repeating unit of the O:2a,c O-specific polysaccharide was assigned the following structure: →4)LGalNAcA(α1 → 3)DQuiNAc(α1 » 3)LRha(α1, where GalNAcA = N-acetylgalactosaminuronic acid, QuiNAc = N-acetylquinovosamine and Rha = rhamnose. The O:2a,b O-specific polysaccharide had the same structure of the trisaccharide repeating unit but was distinguished by the presence of O-acetyl groups on 70–80% of the rhamnose residues in position 2. The O-acetyl groups were located both by methylation with methyltrifluoromethane sulphonate and by comparison of the 13C nuclear magnetic resonance spectra of the native and O-deacetylated polysaccharides. Serological studies revealed the determinant role of the O-acetyl groups in the O-antigen O:2a,b and suggested the O-factor 2b to be related to the 2-O-acetyl-L-rhamnose residue, whereas the O-factor 2c was probably determined by the nonacetylated rhamnose residue. The dominant moiety of the determinant 2a common to the two antigens was obviously presented by the N-acetyl-L-galactosaminuronic acid residue. [ABSTRACT FROM AUTHOR]

A loosely bound lipopolysaccharide-protein complex was extracted from cells of Pseudomonas aeruginosa strain 170015 (O:7ab; Lanyi classification) by saline solution and purified from contaminant nucleic acid by Cetavlon treatment followed by precipitation in an ultracentrifuge. The saline-treated cells were re-extracted with hot aqueous phenol to give firmly bound lipopolysaccharide which was isolated from the phenol layer and purified by ultracentrifugation. The identity of both lipopolysaccharide preparations was proved by serological and chemical evidence. Mild acid degradation of the lipopolysaccharide resulted the splitting off of a lipid component and led to polysaccharide which was purified by gel-filtration on a Sephadex G-50 column. The polysaccharide consisted of N-acetyl-D-fucosamine, N-acetyl-L-fucosamine and D-glucose in the ratio 1:1:1. On the basis of nuclear magnetic resonance spectra, results of methylation analysis and two sequential Smith degradations, the following structure can be assigned to the repeating unit of the polysaccharide: -3)LFucNAc(αl-3)DFucNAc(β1-2)DGlc(β1-. The polysaccharide did not show serological activity whereas alkali-treated lipopolysaccharide readily sensitised sheep erythrocytes and inhibited the passive haemagglutination reaction with anti-(O:7a,b)serum. Evidence is presented that the oligosaccharide repeating units of the polysaccharide and alkali-treated lipopolysaccharide are indistinguishable. Ps. aeruginosa strain 170016 (O:7a,c) was shown to have the O-specific lipopolysaccharide identical with that from strain 170015. The presented data show that subfactors 7b,and 7c in the Lanyi classification of Ps. aeruginosa O-antigens seem to relate to components of the bacterial surface other than lipopolysaccharides. [ABSTRACT FROM AUTHOR]

Two lipopolysaccharide preparations were obtained from Escherichia coli 058 by extraction with 45% aqueous phenol and fractional precipitation with cetyltrimethyl ammonium bromide (Cetavlon). Chemical analysis and polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate showed that the two preparations differed only in the extent of the O-specific polysaccharide moiety. The O-specific polysaccharide was characterized with proton magnetic resonance and infrared spectroscopy, optical rotation and paper electrophoresis. Using gas-liquid chromatography and ion-exchange chromatography, it was shown to contain D-mannose, 2-acetamido-2-deoxy-D-glucose, 3-O-(R-1'-carboxyethyl)-L-rhamnose (rhamnolactylic acid), and O-acetyl groups in the molar ratios of 2:1:1:1. The polysaccharide and oligosaccharides obtained from it were subjected to methylation and chromic acid oxidation. The results obtained indicated that the polysaccharide consists of tetrasaccharide repeating units in which the trisaccharide β-GlcNAc1-4αMan-1-4(2/3-O-Ac)-Man is substituted at C-3 of the non-acetylated mannose with rhamnolactylic acid. The repeating units are joined through α-mannosyl-1-3-glucosamine bonds. This structure is identical with that of the cell wall polysaccharide of Shigella dysenteriae type 5. [ABSTRACT FROM AUTHOR]

The O-specific polysaccharide obtained from Shigella dysenteriae type-2 lipopolysaccharide by mild acid hydrolysis consisted of N-acetylgalactosamine, N-acetylglucosamine, D-galactose, D-glucose, and O-acetyl group in the ratio of 2:1:1:1:1. A number of oligosaccharides were obtained by deamination of the N-deacetylated polysaccharide and by Smith degradation of the both native and O-deacetylated polysaccharides. The identification of oligosaccharides along with methylation analysis and chromic anhydride oxidation showed that the polysaccharide was built up of the repeating pentasaccharide units whose proposed structure is given below: -3αD-GalNAcp1-3αD-GalNAcp1-4αD-Glcp1-4βD-Galp1-3(4)AcαD-GlcNAcp1 [This symbol cannot be presented in ASCII format] Serological properties of Sh. dysenteriae O-specific polysaccharides are discussed. [ABSTRACT FROM AUTHOR]

The O-specific polysaccharide obtained from the lipopolysaccharide of Shigella dysenteriae type 1 (Shigella shiga) by mild acid hydrolysis followed by fractionation on Sephadex G-50 was found to be identical to that described by Morgan's group and was composed of L-rhamnose, D-galactose and N-acetyl-D-glucosamine in a ratio 2:1:1. On the basis of methylation analysis data the polysaccharide was proved to be a linear chain of monosaccharide residues in pyranose forms substituted at position 3, except for that of galactose substituted at position 2. Selective cleavage, based on the N-deacetylation reaction of the polymer, together with determination of linkage configurations by chromic anhydride oxidation showed that the O-specific polysaccharide is built up of repeating tetrasaccharide units whose proposed structure is given below [This symbol cannot be presented in ASCII format] where Rhap = rhamnopyranose, Galp = galactopyranose, and GlcNAcp = N-acetyl-glucosamine. The present findings confirmed the considerations of Heidelberger on the substitution patterns of n-rhamnose and D-galactose residues from the results of serological studies. [ABSTRACT FROM AUTHOR]

O-specific polysaccharides, obtained on mild acid degradation of lipopolysacchrides of the serologically related strains Pseudomonas aeruginosa O3 (L´nyi classification), O25 (Wokatsch classification) and immunotypes 3 and 7 (Fisher classification), are built up of trisaccharide repeating units involving 2-acetamido-2,6-dideoxy-D-galactose (N-acetyl-D-fucosamine), 2,3-diacetarnido-2,3-dideoxy-D-mannuronic acid or 2,3-diacetamido-2,3-dideoxy-L-guluronic acid and 3-acetamidino-2-acetamido-2,3-dideoxy-D-mannuronic acid or 3-acetamidino-2-acetamido-2,3-dideoxy-L-guluronic acid. Lányi O3(a),3d,3f and Wokatsch O25 polysaccharides contain also O-acetyl groups. On the basis of solvolysis with anhydrous hydrogen fluoride, resulting in trisaccharide fragments with N-acetylfucosamine residue at the reducing terminus, chemical modifications of the acetamidino group (alkaline hydrolysis to the acetamido group or reductive deamination to the ethylarnino group), as well as analysis by ¹H-NMR (including nuclear Overhauser effect experiments) and 13C-NMR spectroscopy, and fast-atom bombardment mass spectrometry, it was concluded that the repeating units of the polysaccharides have the following structures: [This equation cannot be converted into ASCII text.] where HexNAcAmA = α-L-GulNAcAmA (≈70%) or β-D-ManNAcAmA (≈30%). Lányi O3(a),3d,3f polysaccharide involves two types of repeating units, which differ from each other only in the configuration at C-5 of the 3-acetamidino-2-acetamido-2,3-dideoxyuronic acid residue. Lányi O3(a),3c, O3a,3d,3e and Fisher immunotypes 3 and 7 polysaccharides contain, together with the major repeating units shown above, a small proportion of units in which the derivative of &aalpha;-L-guluronic acid is replaced by the corresponding β-D-manno isomer. The data obtained provide the opportunity to substantiate the serological interrelations between these strains of P. aeruginosa by the presence in the O-specific polysaccharides of common monosaccharides or disaccharide fragments. The distinctions between them stem from the presence or absence of the O-acetyl group, a different configuration of the glycosidic linkage of the N-acetylfucosamine residue and/or a different configuration at C-5 of one or both derivatives of diaminouronic acids. [ABSTRACT FROM AUTHOR]

The lipopolysaccharides from two serologically related strains of Pseudomonas aeruginosa II (Sandvik classification) and V (IM-1, Verder-Evans classification) were isolated by the Westphal method and cleaved with 1% acetic acid. The O-specific polysaccharide from Sandvik II lipopolysaccharide involved L-rhamnose, N-acetyl-D-quinovosamine, and N-acetyl-D-galactosaminuronic acid in the ratio 2:1:1, as well as O-acetyl groups. The Verder-Evans V O-specific polysaccharide was found to contain just the same sugars and, in addition, D-glucose, the monosaccharide ratio being 2:1:1:1. On the basis of methylation analysis, Smith degradation, solvolysis with anhydrous hydrogen fluoride and ¹H and 13C nuclear magnetic resonance data, it was concluded that the polysaccharides have identical main chains, and there were established the following structures of their repeating units: ... The data obtained allow us to substantiate the combining of the strains studied into one O-serogroup as two individual O-serotypes. [ABSTRACT FROM AUTHOR]

Lipolysaccharides were isolated from dry bacterial cells of Pseudomonas aeruginosa O5a,b,c, O5a,b,d, O5a,d (Lányi classification) and immunotype 6 (Fisher classification) by the Westphal procedure. Their polysaccharide chains were built up of trisaccharide repeating units containing D-xylose, 2- acetamido-2,6-dideoxy-D-galactose and a new sialic acid-like sugar, the di-N-acyl derivative of 5,7-diamino- 3,5,7,9-tetradeoxy-L-glycero-L-manno-nonulosonic (pseudaminic) acid. Formyl, acetyl and (R)-3-hydroxybutyryl groups were identified as the N-acyl substituents of the last monosaccharide; O5a,b,c and O5a,b,d lipopolysaccharides also contained O-acetyl groups. The glycosidic linkage of pseudaminic acid was extremely labile towards acids, and mild acid degradation of the lipopolysaccharides produced, instead of the O-specific polysaccharides, their trisaccharide fragments with pseudamiuic acid at the reducing terminus. Similar degradation of immunotype 6 lipopolysaccharides, followed by oxidation with sodium metaperiodate, resulted in a disaccharide fragment due to destruction of xylose. In contrast the glycosidic linkage of pseudaminic acid proved to be more stable towards treatment with hydrogen fluoride than those of xylose and N-acetylfucosamine. As a result, solvolysis of immunotype 6 lipopolysaccharide with hydrogen fluoride in methanol gave methyl glycosides of a disaccharide and a trisaccharide with pseudaminic acid at the non-reducing terminus. Mild acid hydrolysis of these oligosides afforded free 5-N-acetyl-7-N-formylpseudaminic acid, which was identified by the 1H and 13C nuclear magnetic resonance data, as well as by the mass spectrum of the corresponding fully methylated aldonic acid. As a result of the identification of all oligosaccharides obtained and comparative analysis of the 13C nuclear magnetic resonance spectra of the oligosaccharides and lipopolysaccharides... [ABSTRACT FROM AUTHOR]

The O-specific polysaccharide, obtained on mild acid degradation of lipopolysaccharide of Pseudomonas aeruginosa O13 (Lányi classification), is built up of trisaccharide repeating units involving 2-acetamidino-2,6-dideoxy-D-glucose (N-acetyl-D-quinovosamine, D-QuiNAc), 2-acetamidino-2,6-dideoxy-L-galactose (L- fucosacetamidine, L-FucAm), and a new sialic-acid-like sugar, 5,7-diacetamido-3,5,7,9-tetradeoxy- D-glycero-L-galacto-nonulosonic acid (Sug), and thus contains simultaneously both acidic and basic functions. Cleavage of the polysaccharide with hydrogen fluoride in methanol revealed the high stability of the glycosidic linkage of the ulosonic acid and afforded methyl glycosides of a disaccharide and a trisaccharide. The structures of the new ulosonic acid and acetamidino group were established by analysing the oligosaccharide fragments by 1H, 13C nuclear magnetic resonance spectrometry, as well as on the basis of their chemical conversions: alkaline hydrolysis of the acetamidino group into acetamido group, reductive deamination with lithium borohydride into the ethylamino group and acetylation with acetic anhydride in pyridine accompanied by intramolecular acylation of the acetamidino function by the ulosonic acid to form a six-membered lactam ring. Identification of the oligosaccharide fragments and comparative analysis of the 13C nuclear magnetic resonance spectra of the oligosaccharides and polysaccharide revealed the following structure of the repeating unit:... [ABSTRACT FROM AUTHOR]

Mild acid degradation of lipopolysaccharides from Pseudomonas aeruginosa O10a and O10a,b (Lányi classification) resulted in O-specific polysaccharides built up of trisaccharide repeating units containing 2-acetamido-2,6-dideoxy-D-glucose (N-acetylquinovosamine, DQuiNAc), 2-acetamido-2,6-dideoxy-D-galactose (N-acetylfucosamine, DFucNAc), and 5-acetamido-3,5,7,9-tetradeoxy-7-[(R)-3-hydroxybutyramido]-L-glycero-L-mannononulosonic acid. The latter is a di-N-acyl derivative of a new sialic-acid-like sugar which was called by us pseudaminic acid (PseN2). A 3-hydroxybutyric acid residue was also found in natural carbohydrates for the first time. In the O10a,b polysaccharide pseudaminic acid carried an O-acetyl group at position 4. For selective cleavage of the O10a polysaccharide, solvolysis with hydrogen fluoride was employed which, owing to the relatively high stability of the glycosidic linkage of pseudaminic acid, led to the disaccharide with this sugar on the non-reducing terminus. Performing the solvolysis in methanol afforded the methyl glycoside of this disaccharide which proved to be more advantageous for further analysis. Carboxyl-reduction made the glycosidic linkage of pseudaminic acid extremely labile, and mild acid hydrolysis of the carboxyl-reduced O10a polysaccharide afforded the trisaccharide with a ketose derivative on the reducing terminus. Establishing the structure of the oligosaccharide fragments obtained and interpreting the 13C nuclear resonance spectra of the polysaccharides allowed to determine the following structure for their repeating units: → 4)DFucNAc(α1 → 3)DQuiNAc(β1 → OCHCH2CO → 7)PseN2Ac(β2 I 41 (R) CH3 OR serotype O10a R = H serotype O10a,b R = Ac In the polysaccharides the N-acetylquinovosamine residue is attached not to pseudaminic acid itself, but to its N-acyl substituent, 3-hydroxybutyryl group, and thus the monomers are linked via both glycosidic and amidic linkages. [ABSTRACT FROM AUTHOR]

Lipopolysaccharides from Pseudomonas aeruginosa Ol (Lányi classification), O3 (Habs classification), O13 and 014 (Wokatsch classification), and strain NCTC 8505, which is also related to serogroup O3 (Habs). have structurally similar O-specific polysaccharide chains built up of tetrasaccharide repeating units involving L-rhamnose (Rha), 2-acetamido-2-deoxy-D-glucose (GlcNAc), 2-acetamido-2-deoxy-L-galacturonic acid (GalNAcA), and a di-N-acyl derivative of bacillosamine (BacN): 2,4-diacetamido-2,4,6-trideoxy-D-glucose or 2-acetamido-2,4,6-trideoxy-4-[(5)-3-hydroxybutyramido]-D-glucose. The latter derivative was obtained free by solvolysis with hydrogen fluoride of carboxyl-reduced Habs O3 polysaccharide, and was identified by 'H-nuclear magnetic resonance spectroscopy and by mass spectrometry of the corresponding methylated alditol. Habs O3, Lanyi O1, and Wokatsch 014 polysaccharides contained O-acetyl groups. Solvolysis with hydrogen fluoride of the native Habs O3 polysaccharide resulted in selective cleavage of the glycosidic linkages of 6-deoxy sugars to give the trisaccharide fragment involving all three N-acylated amino sugars. Similar solvolysis of NCTC 8505 polysaccharide afforded a mixture of disaccharide and trisaccharide with N,N'-diacetylbacillosamine at the reducing end. Smith degradation of Habs O3 polysaccharide resulted in selective oxidation of rhamnose to give a glycoside of a trisaccharide with glyceraldehyde as the aglycone. Smith degradation of NCTC 8505 polysaccharide was complicated by the formation of the glycoside of a trisaccharide with an aglycone of unknown structure. A trisaccharide with rhamnose at the reducing end was also isolated after Smith degradation of the latter polysaccharide. Analysis of the composition and structure of all oligosaceharides obtained, and detailed examination of the 13C-nuclear magnetic resonance spectra of these oligosaceharides, and of both intact and modified polysaccharides, revealed the following structures of the repeating units. The structure for the NCTC 8505 polysaccharide differs from that proposed previously [Tahara, Y. and Wilkinson, S. G. (1983) Eur. J. Biochem. 134. 299 - 304] in the configurations assigned to the glycosidic linkages of rhamnose and bacillosamine. The results obtained show the P. aeruginosa strains studied to represent three different O-serotypes in a single O-serogroup. [ABSTRACT FROM AUTHOR]