Structural studies of the O polysaccharides from the lipopolysaccharides of Azospirillum thiophilum BV-ST and Azospirillum griseum L-25-5w-1T

Diazotrophic bacteria of the genus Azospirillum are known widely, because they are ubiquitous in the rhizosphere and can promote the growth and performance of nonlegume plants. Recently, more Azospirillum species have been isolated from sources other than plants or soil. We report the structures of the O polysaccharides (OPSs) from the lipopolysaccharides of the type strains A. thiophilum BV-ST (1) and A. griseum L-25-5w-1T (2), isolated from aquatic environments. Both structures have a common tetrarhamnan in the repeating-unit, which is decorated with a side xylose in the OPS of A. thiophilum BV-ST.

Structure of the O-polysaccharide from the moderately halophilic bacterium Halomonas fontilapidosi KR26

Lipopolysaccharide was obtained from the aerobic moderately halophilic bacterium Halomonas fontilapidosi KR26. The O-polysaccharide was isolated by mild acid degradation of the lipopolysaccharide and was examined by chemical methods and by 1H and 13C NMR spectroscopy, including 1H,1H COSY, TOCSY, ROESY, and 1H,13C HSQC, and HMBC experiments. The following structure of the linear tetrasaccharide repeating unit was deduced. →2)-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→3)-β-d-Galp-(1→.

Structure of the O-specific polysaccharide of Ochrobactrum endophyticum KCTC 42485T containing 3-(3-hydroxy-2,3-dimethyl-5-oxoprolyl)amino-3,6-dideoxy-d-galactose

Ochrobactrum endophyticum (syn. Brucella endophytica) is an aerobic species of Alphaproteobacteria isolated from healthy roots of Glycyrrhiza uralensis. Here we report the structure of the O-specific polysaccharide obtained by mild acid hydrolysis of the lipopolysaccharide of the type strain KCTC 42485:→3)-α-l-FucpNAc-(1→3)-β-d-QuipNAc-(1→2)-β-d-Fucp3NAcyl-(1→ where Acyl is 3-hydroxy-2,3-dimethyl-5-oxoprolyl. The structure was elucidated using chemical analyses along with ¹H and ¹³C NMR spectroscopy (including ¹H,¹H COSY, TOCSY, ROESY and ¹H,¹³C HSQC, HMBC, HSQC-TOCSY and HSQC-NOESY experiments). To our knowledge the OPS structure is novel and has not been previously published.

Structure and gene cluster of the O-antigen of Enterobacter cloacae G3422

The O-polysaccharide (OPS) was isolated by mild acid degradation of the lipopolysaccharide of Enterobacter cloacae G3422 and studied by chemical methods, including sugar analyses, Smith degradation, and solvolysis with anhydrous trifluoroacetic acid, along with ¹H and ¹³C NMR spectroscopy. The following structure of the branched tetrasaccharide repeating unit was established: The O-antigen gene cluster of Enterobacter cloacae G3422 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in a good agreement with the O-antigen structure.

Structure and genetics of the O-antigen of Enterobacter cloacae K7 containing di-N-acetylpseudaminic acid

The O-antigen (O-polysaccharide) is an essential component of lipopolysaccharide on the surface of Gram-negative bacteria and plays an important role in interaction with host organisms. In this study, we investigated the chemical structure and characterized the gene cluster of Enterobacter cloacae K7 O-antigen. As judged by sugar analyses along with NMR spectroscopy data, E. cloacae K7 antigen has a tetrasaccharide O-unit with the following structure: →8)-β-Psep5Ac7Ac-(2 → 2)-β-l-Rhap-(1 → 4)-α-l-Rhap-(1 → 3)-α-d-Galp-(1→ The O-antigen gene cluster of E. cloacae K7 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases.

Structure elucidation and gene cluster annotation of the O-antigen of Pseudomonas veronii SHC-8-1 containing 2-acetamido-2,4,6-trideoxy-4-(3,5-dihydroxyhexanoylamino)-d-glucose

O-polysaccharide (O-antigen, OPS) was isolated from the lipopolysaccharide of Pseudomonas veronii SHC-8-1 and studied by component analyses and 1D and 2D NMR spectroscopy. The following structure of the O-polysaccharide was established: where QuipNAc4N(dHh) is 2,4-diamino-2,4,6-trideoxy-dglucose (Bacillosamine) in which N-2 is acetylated and N-4 is acylated with 3,5-dihydroxyhexanoic acid (dHh). The O-antigen gene cluster of Pseudomonas veronii SHC-8-1 has been sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the OPS structure.

Structure and gene cluster of the O-antigen of Escherichia coli strain SDLZB008

The O-polysaccharide (O-antigen) of Escherichia coli SDLZB008 was isolated from the lipopolysaccharide and studied by sugar analyses along with ¹H and ¹³C NMR spectroscopy. The following structure of the branched pentasaccharide repeating unit was established, which is unique among the known structures of bacterial polysaccharides: The O-antigen gene cluster of E. coli SDLZB008 has been sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-polysaccharide structure.

Structure of the O-antigen of a halophilic bacterium Salinicola salarius HO-14

The structure of the O-polysaccharide of an aerobic halophilic bacterium Salinicola salarius HO-14 isolated from a heavy oil reservoir with highly mineralized water was determined. The neutral O-polysaccharide of strain HO-14 was isolated from the lipopolysaccharide and studied by sugar analysis and NMR spectroscopy. The linear tetrasaccharide repeating unit was found to have the following structure: →2)-α-l-Rhap-(1 → 3)-β-l-Rhap-(1 → 2)-α-l-Rhap-(1 → 2)-α-d-Manp-(1→.

The unique structure of bacterial polysaccharides - Immunochemical studies on the O-antigen of Proteus penneri 4034-85 clinical strain classified into a new O83 Proteus serogroup

The serological classification scheme of the opportunistic Proteus bacilli includes a number of Proteus penneri strains. The tested P. penneri 4034-85 strain turned out to be serologically distinguished in ELISA and Western blotting. The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of this strain and studied by sugar and methylation analyses and dephosphorylation along with ¹H and ¹³C NMR spectroscopy, including 2D ¹H,¹H COSY, TOCSY, ROESY, ¹H,¹³C HSQC, HMBC, and HSQC-TOCSY experiments, The O-polysaccharide was found to have a linear repeating unit containing glycerol 1-phosphate and two residues each of Gal and GlcNAc. The following O-polysaccharide structure was established, which, to our knowledge, is unique among known bacterial polysaccharide structures.

Structure elucidation and gene cluster characterization of the O-antigen of Yersinia kristensenii С-134

Mild acid degradation of the lipopolysaccharide of Yersinia kristensenii C-134 afforded a glycerol teichoic acid-like O-polysaccharide, which was studied by sugar analysis, O-deacetylation and dephosphorylation along with 1D and 2D NMR spectroscopy. The following structure of the O-polysaccharide was established: This structure is related to those of other Y. kristensenii O-polysaccharides studied earlier. The O-antigen gene cluster of Y. kristensenii С-134 was analyzed and found to be consistent with the O-polysaccharide structure established.

Colitose-containing O-polysaccharide structure and O-antigen gene cluster of Escherichia albertii HK18069 related to those of Escherichia coli O55 and E. coli O128

A 3,6-dideoxy-l-xylo-hexose (colitose)-containing partially O-acetylated branched polysaccharide was obtained by mild acid hydrolysis (2% HOAc, 100 °C, 2 h) of the lipopolysaccharide of Escherichia albertii HK18069 followed by gel-permeation chromatography on Sephadex G-50 Superfine. Part of colitose residues (~40%) was cleaved upon hydrolysis, and the full cleavage was achieved by prolonged hydrolysis (8 h) under the same conditions and resulted in a modified linear polysaccharide. Structure of the O-polysaccharide of E. albertii HK18069 was established by 1D and 2D ¹H and ¹³C NMR spectroscopy applied to both initial and modified O-deacetylated and colitose-free polysaccharides: where β-d-Galp is mono-O-acetylated at position either 3 (~50%) or 4 (~30%). The O-antigen gene cluster of E. albertii HK18069 between conserved galF and gnd genes together with flanking regions was sequenced, and predicted functions of the genes were found to be consistent with the O-polysaccharide structure established. The O-polysaccharide structure and the O-antigen gene cluster of E. albertii HK18069 are related to those of Esherichia coli O55 and E. coli O128 reported earlier. It is proposed to create for strain HK18069 a new E. albertii O-serogroup, O8.

Structure of the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71T

O-specific polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide of plant-growth-promoting rhizobacteria Azospirillum doebereinerae GSF71^T and studied by sugar analysis along with ¹H and ¹³C NMR spectroscopy, including 2D ¹H,¹H COSY, TOCSY, ROESY, ¹H,¹³C HSQC, and HMBC experiments. It was established that the polysaccharide is linear and consists of tetrasaccharide repeating units with the following structure.

Structure and gene cluster of the O-polysaccharide of Yersinia rohdei H274-36/78

A branched O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Yersinia rohdei H274-36/78 and found to contain d-rhamnose, d-mannose, and 3,6-dideoxy-4-C-[(S)-1-hydroxyethyl]-d-xylo-hexose called yersiniose A (Yer). Partial acid hydrolysis of the O-polysaccharide eliminated Yer residues to give a modified linear polysaccharide. Studies by sugar analysis and ¹H and ¹³C NMR spectroscopy, including computational NMR analysis, enabled structure elucidation of a hexasaccharide repeating unit of the O-polysaccharide having two Yer residues attached as monosaccharide side chains. The O-antigen gene cluster of Y. rohdei H274-36/78 located between JUMPStart and galF genes contained putative genes for synthesis of precursors of two O-antigen constituents, GDP-d-Man and GDP-d-Rha, whereas genes responsible for synthesis of CDP-Yer were within the chromosome outside the O-antigen gene cluster. Glycosyltransferase genes and ABC 2 transporter genes were present in the O-antigen gene cluster, and hence the structure established is consistent with the polysaccharide synthesis gene content of the genome.

Structure elucidation and gene cluster annotation of the O-antigen of Vibrio cholerae O100 containing two rarely occurred amino sugar derivatives

O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of Vibrio cholerae O100 and studied by component analyses and 1D and 2D NMR spectroscopy. The following structure of the O-polysaccharide was established: →3)-β-d-QuipNAc4N(dHh)-(1 → 3)-α-d-Fucp4N(RHb)-(1 → 3)-α-l-FucpNAc-(1→ where Hb and dHh indicate 3-hydroxybutanoyl and 3,5-dihydroxyhexanoyl, respectively. The O-antigen gene cluster of V. cholerae O100 has been sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the OPS structure.

Chemical characterization and serological properties of a unique O-polysaccharide of the Proteus mirabilis Sm 99 clinical strain - Identification of a new, O81, serotype

The current serological classification scheme of the medically important bacteria from the genus Proteus consists of 80 O serogroups, the last four of which (O77-O80) were created from clinical strains from Łódź, Poland. There are more serologically unique strains isolated from patient that do not fit into the existing scheme, such as Proteus mirabilis strain Sm 99 isolated from urine of a 74-year-old woman in Łódź. Serological investigation involving ELISA and Western blotting failed to classify the Proteus mirabilis strain Sm 99 into any of the 80 Proteus O serogroups. Sugar analysis along with two-dimensional NMR spectroscopy showed that the O-polysaccharide is composed of branched pentasaccharide repeating units containing one residue each of d-Glc, d-GlcNAc, d-GalNAc, d-glucuronic acid, and 4-[(R)-3-hydroxybutanoylamino]-4,6-dideoxy-d-glucose. The chemical and serological data show that the O antigen of P. mirabilis Sm 99 is unique among the known Proteus O antigens. Based on this finding, it is proposed to extend the current serological classification scheme of Proteus by adding a new serogroup, O81, which at present consists of P. mirabilis strain Sm 99 only.

Structure of the O-specific polysaccharide from Azospirillum fermentarium CC-LY743T

O-specific polysaccharide was obtained by mild acid hydrolysis of the lipopolysaccharide of nitrogen-fixing bacterium Azospirillum fermentarium CC-LY743^T (IBPPM 578) and was studied by sugar analysis along with ¹H and ¹³C NMR spectroscopy, including ¹H,¹H COSY, TOCSY, ROESY, and ¹H,¹³C HSQC and HMBC experiments. The polysaccharide was found to be linear and to consist of alterating α-l-fucose and α-d-mannose residues in tetrasaccharide repeating units of the following structure: →2)-α-D-Manp-(1 → 3)-α-L-Fucp-(1 → 3)-α-D-Manp-(1 → 3)-α-L-Fucp-(1→.

Structure and gene cluster of the K125 capsular polysaccharide from Acinetobacter baumannii MAR13-1452

A capsular polysaccharide (CPS) was isolated from strain MAR13-1452 of an emerging pathogen Acinetobacter baumannii and assigned type K125. The following structure of the CPS was established by sugar analysis, Smith degradation, and 1D and 2D ¹H and ¹³C NMR spectroscopy: Proteins encoded by the KL125 gene cluster in the genome of MAR13-1452, including three glycosyltransferases, were assigned roles in the biosynthesis of the K125 CPS.

Structural studies on the O-polysaccharide of Escherichia coli O57

Mild acid hydrolysis of the lipopolysaccharide of Escherichia coli O57 afforded an O-polysaccharide, which was isolated by gel permeation chromatography (GPC) and studied by sugar analysis, Smith degradation and solvolysis with trifluoroacetic acid, along with 2D ¹H and ¹³C NMR spectroscopy. The O-polysaccharide was found to contain d-Glc, d-Gal, d-GalA, d-GlcNAc, and l-FucNAc, as well as O-acetyl groups. Smith degradation of the O-deacetylated polysaccharide destroyed side-branch β-Glсp and α-GalpA to give a modified linear polysaccharide. Solvolysis cleaved selectively the linkage of α-l-FucpNAc to give a pentasaccharide corresponding to the O-polysaccharide repeat. A comparison of the NMR spectra of the initial and O-deacetylated polysaccharides showed that α-GalpA is non-stoichiometrically O-acetylated at position either 2 (∼30%) or 3 (∼40%). The following structure of the O-polysaccharide was established, which is unique among known bacterial polysaccharide structures.

Structural and genetic relatedness of the O-antigens of Escherichia coli O50 and O2

An O-specific polysaccharide (O-antigen) was isolated by mild acid degradation of the lipopolysaccharide of Escherichia coli O50 followed by gel chromatography on Sephadex G-50. The following structure of the tetrasaccharide repeat was established by sugar analysis and 1D and 2D ¹H and ¹³C NMR spectroscopy: →3)-α-l-Rhap-(1 → 2)-α-l-Rhap-(1 → 3)-β-l-Rhap-(1 → 4)-β-d-GlcpNAc-(1→ The linear O50 polysaccharide has the same structure as the main chain of the branched O polysaccharide of E. coli O2 studied earlier [Jansson et al., Carbohydr. Res. 161 (1987) 273-279], which differs in the presence of a side-chain α-d-Fucp3NAc residue. In spite of the difference between the O-polysaccharides, the corresponding genes in the O2- and O50-antigen gene cluster are 99-100% identical. The genetic basis for the lack of d-Fucp3NAc from the O50 polysaccharide is evidently a point mutation in the aminotransferase gene fdtB of the d-Fucp3NAc synthesis pathway resulting in a single amino acid change from histidine in O2 to arginine in O50.

Full structure and insight into the gene cluster of the O-specific polysaccharide of Yersinia intermedia H9-36/83 (O:17)

Lipopolysaccharide was isolated from bacteria Yersinia intermedia H9-36/83 (O:17) and degraded with mild acid to give an O-specific polysaccharide, which was isolated by GPC on Sephadex G-50 and studied by sugar analysis and 1D and 2D NMR spectroscopy. The polysaccharide was found to contain 3-deoxy-3-[(R)-3-hydroxybutanoylamino]-d-fucose (d-Fuc3NR3Hb) and the following structure of the heptasaccharide repeating unit was established: The structure established is consistent with the gene content of the O-antigen gene cluster. The O-polysaccharide structure and gene cluster of Y. intermedia are related to those of Hafnia alvei 1211 and Escherichia coli O:103.

Structure and gene cluster of the O-antigen of Escherichia coli O54

Mild acid hydrolysis of the lipopolysaccharide of Escherichia coli O54 afforded an O-polysaccharide, which was studied by sugar analysis, solvolysis with anhydrous trifluoroacetic acid, and ¹H and ¹³C NMR spectroscopy. Solvolysis cleaved predominantly the linkage of β-d-Ribf and, to a lesser extent, that of β-d-GlcpNAc, whereas the other linkages, including the linkage of α-l-Rhap, were stable under selected conditions (40 °C, 5 h). The following structure of the O-polysaccharide was established: →4)-α-d-GalpA-(1 → 2)-α-l-Rhap-(1 → 2)-β-d-Ribf-(1 → 4)-β-d-Galp-(1 → 3)-β-d-GlcpNAc-(1→ The O-antigen gene cluster of E. coli O54 was analyzed and found to be consistent in general with the O-polysaccharide structure established but there were two exceptions: i) in the cluster, there were genes for phosphoserine phosphatase and serine transferase, which have no apparent role in the O-polysaccharide synthesis, and ii) no ribofuranosyltransferase gene was present in the cluster. Both uncommon features are shared by some other enteric bacteria.

Studies on the O-polysaccharide of Escherichia albertii O2 characterized by non-stoichiometric O-acetylation and non-stoichiometric side-chain l-fucosylation

An O-polysaccharide was isolated from the lipopolysaccharide of Escherichia albertii O2 and studied by chemical methods and 1D and 2D ¹H and ¹³C NMR spectroscopy. The following structure of the O-polysaccharide was established: . The O-polysaccharide is characterized by masked regularity owing to a non-stoichiometric O-acetylation of an l-fucose residue in the main chain and a non-stoichiometric side-chain l-fucosylation of a β-GlcNAc residue. A regular linear polysaccharide was obtained by sequential Smith degradation and alkaline O-deacetylation of the O-polysaccharide. The content of the O-antigen gene cluster of E. albertii O2 was found to be essentially consistent with the O-polysaccharide structure established.

Structure and genetics of a glycerol 2-phosphate-containing O-specific polysaccharide of Escherichia coli O33

An O-specific polysaccharide was isolated by mild acid degradation of the lipopolysaccharide of Escherichia coli O33 followed by gel-permeation chromatography on Sephadex G-50. The polysaccharide was found to contain glycerol 2-phosphate (Gro-2-P), and the following structure of its tetrasaccharide repeat was established by sugar analysis, dephosphorylation, and 1D and 2D ¹H and ¹³C NMR spectroscopy: The O33-antigen gene cluster was analyzed and found to be essentially consistent with the O-polysaccharide structure.

Structure elucidation of the O-specific polysaccharide by NMR spectroscopy and selective cleavage and genetic characterization of the O-antigen of Escherichia albertii O5

The O-specific polysaccharide (O-antigen) was obtained by mild acid degradation of the lipopolysaccharide of Escherichia albertii O5 (strain T150248) and studied by sugar analysis, selective cleavages of glycosidic linkages, and 1D and 2D ¹H and ¹³C NMR spectroscopy. Partial solvolysis with anh (anhydrous) CF₃CO₂H and hydrolysis with 0.05 M CF₃CO₂H cleaved predominantly the glycosidic linkage of β-GalpNAc or β-Galf, respectively, whereas the linkages of α-GlcpNAc and β-Galp were stable. Mixtures of the corresponding tri- and tetra-saccharides thus obtained were studied by NMR spectroscopy and high-resolution ESI MS. The following new structure was established for the tetrasaccharide repeat (O-unit) of the O-polysaccharide: →4)-α-d-GlcpNAc-(1 → 4)-β-d-Galp6Ac-(1 → 6)-β-d-Galf-(1 → 3)-β-d-GalpNAc-(1→where the degree of O-acetylation of d-Galp is ∼70%. The O-polysaccharide studied has a β-d-Galp-(1 → 6)-β-d-Galf-(1 → 3)-β-d-GalpNAc trisaccharide fragment in common with the O-polysaccharides of E. albertii O7, Escherichia coli O124 and O164, and Shigella dysenteriae type 3 studied earlier. The orf5-7 in the O-antigen gene cluster of E. albertii O5 are 47%, 78%, and 75% identical on the amino acid level to genes for predicted enzymes of E. albertii O7, including Galp-transferase wfeS, UDP-d-Galp mutase glf, and Galf-transferase wfeT, respectively, which are putatively involved with the synthesis of the shared trisaccharide fragment of the O-polysaccharides. The occurrence upstream of the O-antigen gene cluster of a 4-epimerase gene gnu for conversion of undecaprenyl diphosphate-linked d-GlcNAc (UndPP-d-GlcNAc) into UndPP-d-GalNAc indicates that d-GalNAc is the first monosaccharide of the O-unit, and hence the O-units are interlinked in the O-polysaccharide of E. albertii O5 by the β-d-GalpNAc-(1 → 4)-α-d-GlcpNAc linkage.

Structural analysis of the O-polysaccharide from the lipopolysaccharide of Pseudomonas putida BIM B-1100

Two specific polysaccharides, together with an →4)-α-d-Glcp-(1→ glucan (bacterial glycogen), were obtained from a lipopolysaccharide preparation isolated from the bacterium Pseudomonas putida BIM B-1100 by phenol/water extraction. The following structures of the polysaccharides were established by composition analysis, Smith degradation, ESI-MS, and 1D and 2D NMR spectroscopy.

Structures and gene clusters of the O-antigens of Escherichia albertii O3, O4, O6, and O7

The O-specific polysaccharides (OPSs) called O-antigens were obtained by mild acid degradation of the lipopolysaccharides of Escherichia albertii serotypes O3, O4, O6, and O7 and studied by sugar analysis along with 1D and 2D ¹H and ¹³C NMR spectroscopy. The following structure was established for the OPS of E. albertii O4, which, to our knowledge, is unique among known bacterial polysaccharide structures: →2)-α-l-Rhap-(1 → 2)-α-l-Fucp-(1 → 2)-β-d-Galp-(1 → 3)-α-d-GalpNAc-(1 → 3)-β-d-GlcpNAc-(1→ The OPS structure of the strain of E. albertii O7 studied was identical to that of strain LMG 20973 (= Albert 10457), whose structure has been reported earlier (R. Eserstam et al. Eur. J. Biochem. 269 (2002) 3289-3295). E. albertii O3 and O6 shared the OPS structures with Escherichia coli O181 and O3, respectively, except for the lack of O-acetylation in E. albertii O3, which is present in E. coli O181. The gene clusters driving the O-antigen biosynthesis of the E. albertii strains were sequenced, the genes were annotated by comparison with sequences in the available databases, and the predicted functions of the encoded proteins were found to be consistent with the OPS structures established. In accordance with the relatedness of the OPS structures, the O-antigen gene clusters of E. albertii O3 and O6 contain the same genes and have the same organization as those of E. coli O181 and O3, the entire gene clusters being 83% and 98% identical, respectively.

Structure and gene cluster of a tyvelose-containing O-polysaccharide of an entomopathogenic bacterium Yersinia entomophaga MH96T related to Yersinia pseudotuberculosis

An O-polysaccharide was isolated from the lipopolysaccharide of an entomopathogenic bacterium Yersinia entomophaga MH96^T by mild acid hydrolysis and studied by 2D NMR spectroscopy. The following structure of the branched tetrasaccharide repeating unit of the polysaccharide was established: where Tyv indicates 3,6-dideoxy-d-arabino-hexose (tyvelose). The structure established is consistent with the gene content of the O-antigen gene cluster. The O-polysaccharide structure and gene cluster of Y. entomophaga are related to those of some Y. pseudotuberculosis serotypes.

Structure and gene cluster of the O-antigen of Escherichia albertii O1 resembling the O-antigen of Pseudomonas aeruginosa O5

The O-specific polysaccharide (O-antigen) was obtained by mild acid degradation of the lipopolysaccharide of Escherichia albertii serotype O1 strain SP20140089 and studied by sugar analysis along with 1D and 2D ¹H and ¹³C NMR spectroscopy. The following structure was established for the trisaccharide repeating unit of the O-polysaccharide: →4)-β-d-ManpNAc3NAcA-(1 → 4)-β-d-GlcpNAm3NAcA-(1 → 3)-α-d-GlcpNAc-(1→ where ManNAc3NAcA and GlcNAm3NAcA indicate 2,3-diacetamido-2,3-dideoxymannuronic acid and 2-acetimidoylamino-3-acetamido-2,3-dideoxyglucuronic acid, respectively. While showing some similarity with O-polysaccharide structures of a group of Pseudomonas aeruginosa serotypes (O2, O5, O16, O18, and O20), that of E. albertii O1 is unique among known bacterial polysaccharide structures. The gene cluster for biosynthesis of the O1-antigen was sequenced and functions of the genes were predicted by comparison with sequences in the available databases, including those involved in the synthesis of nucleotide precursors of 2,3-diamino-2,3-dideoxyhexuronic acid derivatives in P. aeruginosa O5.

Structural and genetic characterization of the O-antigen of Enterobacter cloacae C5529 related to the O-antigen of E. cloacae G3054

On mild acid degradation of the lipopolysaccharide of Enterobacter cloacae C5529, the O-polysaccharide chain was cleaved at the linkages of 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Psep5Ac7Ac). The resultant oligosaccharide and an alkali-treated lipopolysaccharide were studied by sugar analysis along with ¹H and ¹³C NMR spectroscopy, and the following structure of the tetrasaccharide repeating unit of the O-polysaccharide was established: →4)-β-Psep5Ac7Ac-(2 → 3)-β-d-Galp-(1 → 6)-β-d-Galf-(1 → 3)-α-d-Galp-(1→ It differs from a structurally related O-polysaccharide of E. cloacae G3045 studied early (Perepelov, A. V.; Wang, M.; Filatov, A. V.; Guo, X.; Shashkov, A. S.; Wang, L.; Knirel, Y. A. Carbohydr. Res. 2015; 407:59-62) in positions of substitution of β-Psep5Ac7Ac (O-4 vs. O-8) and β-Galp (O-3 vs. O-6) and the absence of a side-chain α-Galp residue. The O-antigen gene clusters of E. cloacae C5529 and G3045 are organized identically and include genes with the same putative functions in the O-polysaccharide synthesis. Based on these and serological data, it is suggested to combine E. cloacae C5529 and G3054 in one O-serogroup as two subgroups.

Structure elucidation and analysis of biosynthesis genes of the O-antigen of Escherichia coli O131 containing N-acetylneuraminic acid

The O-polysaccharide (O-antigen) of Escherichia coli O131 was studied by sugar analysis along with 1D and 2D ¹H and ¹³C NMR spectroscopy. The following structure of the linear tetrasaccharide repeating unit of the polysaccharide was established: →8)-α-Neup5Ac-(2 → 6)-β-D-Galp-(1 → 6)-β-D-Galp-(1 → 3)-β-D-GalpNAc-(1→ The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the E. coli O131-antigen structure.

Structure and genetics of the O-antigens of Escherichia coli O182-O187

O-polysaccharides (OPSs) were obtained by mild acid degradation of the lipopolysaccharides of Escherichia coli O182-O187, and their structures were established by sugar analysis, Smith degradation, and ¹H and ¹³C NMR spectroscopy. In addition to the monosaccharides that occur often in E. coli OPSs (d-Glc, d-Gal, d-Man, d-GlcNAc, d-GalNAc, d-GlcA, l-Fuc, d-Rib), a number of less common components were identified as the OPS constituents, including 2-acetamido-2-deoxy-l-quinovose and 4-deoxy-4-[(S)-3-hydroxybutanoyl-l-alanyl]-d-quinovose (O186), 3-acetamido-3-deoxy-d-fucose (O187), 3-deoxy-3-[(R)-3-hydroxybutanoyl]-d-fucose (O184), and 2,3-diacetamido-2,3-dideoxy-l-rhamnose (O182). The OPS structures of E. coli O183 and O182 are identical to those of the OPS of Shigella boydii type 10 and the capsular polysaccharide of E. coli K48, respectively. The OPSs of E. coli O186 and O123 are closely related differing in the presence of a Glc residue in the former in place of a GlcNAc residue in the latter. The O-antigen gene clusters of the bacteria studied were analyzed and their contents were found to be consistent with the OPS structures. Predicted glycosyltransferases encoded in the gene clusters were tentatively assigned to glycosidic linkages based on similarities to sequences of other E. coli O-serogroups available from GenBank and taking into account the OPS structures established.

Structure elucidation and gene cluster characterization of the O-antigen of Escherichia coli O80

Mild alkaline degradation of the lipopolysaccharide of Escherichia coli O80 afforded a polysaccharide, which was studied by sugar analysis, selective cleavage of glycosidic linkages, and (1)H and (13)C NMR spectroscopy. Solvolysis of the polysaccharide with CF3CO2H cleaved the linkages of α-Fuc and β-linked GlcNAc and GalNAc residues to give two disaccharides. The following structure of the hexasaccharide repeating unit of the O-polysaccharide was established: The polysaccharide repeat also contains a minor O-acetyl group but its position was not determined. The O-antigen gene cluster of E. coli O80 between the conserved galF and gnd genes was analyzed and found to be consistent with the O-polysaccharide structure established.

Structure and gene cluster of the O-antigen of Escherichia coli O156 containing a pyruvic acid acetal

The lipopolysaccharide of Escherichia coli O156 was degraded under mild acidic and alkaline conditions and the resulting polysaccharides were studied by sugar analysis and (1)H and (13)C NMR spectroscopy. The following structure of the pentasaccharide repeating unit of the O-polysaccharide was established: where Rpyr indicates R-configurated pyruvic acid acetal. Minor O-acetyl groups also were present and tentatively localized on the Gal residues. The gene cluster for biosynthesis of the O-antigen of E. coli O156 was analyzed and shown to be consistent with the O-polysaccharide structure.

Structure of the β-l-fucopyranosyl phosphate-containing O-specific polysaccharide of Escherichia coli O84

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-Fucp-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-Fucp-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.

Structure of the O-polysaccharide of Escherichia coli O132

Mild acid degradation of the lipopolysaccharide of Escherichia coli O132 released its O-polysaccharide. Analysis by 1D and 2D (1)H and (13)C NMR spectroscopy prior and subsequent to O-deacetylation, in conjunction with sugar analysis, revealed a linear pentasaccharide repeating unit of the O-polysaccharide having the following structure: →2)-α-d-Galf-(1→3)-α-l-Rhap2Ac-(1→4)-α-d-Glcp-(1→2)-α-l-Rhap-(1→3)-β-d-GlcpNAc-(1→ Putative functions of genes in the O-antigen gene cluster of E. coli O132 are consistent with the O-polysaccharide structure.

Structures and genetics of biosynthesis of glycerol 1-phosphate-containing O-polysaccharides of Escherichia coli O28ab, O37, and O100

O-polysaccharides of E. coli O28ab, O37, and O100 were found to contain glycerol 1-phosphate and the following structures of their oligosaccharide repeats were established by sugar analysis, Smith degradation (for O28ab), 1D and 2D (1)H, (13)C, and (13)P NMR spectroscopy: [Formula: see text]. Functions of putative glycosyltransferases genes in the O-antigen gene clusters of the strains studied were tentatively assigned based on similarities to genes of other E. coli O-serogroups available from GenBank and taking into account the O-polysaccharide structures established.

Structure and gene cluster of the O-antigen of Escherichia coli O137

The O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of Escherichia coli O137 and studied by sugar analysis and NMR spectroscopy. The following structure of the branched tetrasaccharide repeating unit was established: Formula: see text] Both structure and gene cluster of the E. coli O137 polysaccharide are related to those of the E. coli K40 polysaccharide (Amor et al., 1999), which lacks the side-chain glucosylation but contains serine that is amide-linked to GlcA. Functions of genes in the O137-antigen gene cluster were assigned by a comparison with those in K40 and sequences in the available databases. Particularly, predicted glycosyltransferases encoded in the gene cluster were assigned to the formation of three glycosidic linkages in the O-polysaccharide repeating unit.

Structure and gene cluster of the o-antigen of Escherichia coli o96

Mild acid degradation of the lipopolysaccharide of Escherichia coli O96 afforded a mixture of two polysaccharides. The following structure of the pentasaccharide repeating unit of the major polymer was established by sugar analysis, Smith degradation, and (1)H and (13)C NMR spectroscopy: [Formula: see text]. The O-antigen gene cluster of E. coli O96 between conserved galF and gnd genes was found to be consistent with this structure, and hence, the major polysaccharide represents the O96-antigen. The O96-antigen structure and gene cluster are similar to those of E. coli O170, and two proteins encoded in the gene clusters of both bacteria were putatively assigned a function of galactofuranosyltransferases. The minor polymer has the same structure as a peptidoglycan-related polysaccharide reported earlier in Providencia alcalifeciens O45 and several other O-serogoups of this species (Ovchinnikova OG, Liu B, Kocharova NA, Shashkov AS, Kondakova AN, Siwinska M, Feng L, Rozalski A, Wang L, Knirel YA. Biochemistry (Moscow) 2012;77:609-15) → 4)-β-D-GlcpNAc-(1 → 4)-β-D-GlcpNAc3(Rlac-lAla)-(1 → where Rlac-lAla indicates (R)-1-[(S)-1-carboxyethylaminocarbonyl]ethyl.

Structure of the polysaccharides from the lipopolysaccharide of Azospirillum brasilense Jm125A2

Two polysaccharides were obtained by mild acid degradation of the lipopolysaccharide of associative nitrogen-fixing bacteria Azospirillum brasilense Jm125A2 isolated from the rhizosphere of a pearl millet. The following structures of the polysaccharides were established by sugar and methylation analyses, Smith degradation, and (1)H and (13)C NMR spectroscopy: [Formula: see text] Structure 1 has been reported earlier for a polysaccharide from A. brasilense S17 (Fedonenko YP, Konnova ON, Zdorovenko EL, Konnova SA, Zatonsky GV, Shaskov AS, Ignatov VV, Knirel YA. Carbohydr Res 2008;343:810-6), whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides.

Structure and genetics of biosynthesis of the glycosyl phosphate-containing O-polysaccharide of Escherichia coli O160

On mild acid degradation of the lipopolysaccharide of Escherichia coli O160, the O-polysaccharide was cleaved by acid-labile glycosyl phosphate linkages in the main chain. The resultant oligosaccharide and the alkali-treated lipopolysaccharide were studied by sugar analysis along with (1)H and (13)C NMR spectroscopies, and the following structure of the branched pentasaccharide repeating unit of the O-polysaccharide was established: The O-antigen gene cluster of E. coli O160 was found to be consistent with the O-polysaccharide structure established.

Structure elucidation and biosynthesis gene cluster organization of the O-antigen of Escherichia coli O170

Enterotoxigenic Escherichia coli are causative agents of diarrhea in humans as well as animals, and E.coli O170 belongs to this virotype. Upon mild acid degradation of the lipopolysaccharide of E.coli O170, the branched O-polysaccharide chain was partially cleaved at β-d-glactofuranosidic linkages to give multiple products, including a linear tetrasaccharide and oligomers thereof. Studies of the acid degradation products and O-deacylated lipopolysaccharide by 1D and 2D (1)H and (13)C NMR spectroscopy enabled elucidation of the following O-polysaccharide structure: Functions of genes in the O-antigen biosynthesis gene cluster were tentatively assigned and found to be in agreement with the O-polysaccharide structure.

Structure and gene cluster of the O-antigen of Escherichia coli O43

The O-polysaccharide (O-antigen) of Escherichia coli O43 was isolated from the lipopolysaccharide and studied by chemical methods, including sugar analyses, Smith degradation, and solvolysis with anhydrous trifluoroacetic acid, along with (1)H and (13)C NMR spectroscopy. The following structure of the pentasaccharide repeating unit of the O-polysaccharide was established: [Formula: see text] Functions of genes in the O-antigen gene cluster of E. coli O43 were assigned by a comparison with sequences in the available databases and found to be in agreement with the O-polysaccharide structure.

Structure and genetics of the O-antigen of Escherichia coli O169 related to the O-antigen of Shigella boydii type 6

The O-polysaccharide (O-antigen) of Escherichia coli O169 was studied by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. The following structure of the branched hexasaccharide repeating unit was established: [Formula: see text] The O-polysaccharide of E. coli O169 differs from that of Shigella boydii type 6 only in the presence of a side-chain glucose residue. A comparison of the O-antigen biosynthesis gene clusters between the galF to gnd genes in the genomes of the two bacteria revealed their close relationship. The glycosyltransferase gene responsible for the formation of the β-D-Glcp-(1 → 6)-α-D-Galp linkage in the O-antigen was identified in the gene cluster.

Structure of the O-polysaccharide of Escherichia coli O87

The following structure of the O-polysaccharide of Escherichia coli HS1/2 serving as a primary receptor for bacteriophage DT57-12 was elucidated by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy: This structure is shared by E. coli O87 type strain. Putatively assigned functions of genes in the O-antigen gene cluster of E. coli O87 are consistent with the O-polysaccharide structure established.

Structure of a zwitterionic O-polysaccharide from Photorhabdus temperata subsp. cinerea 3240

A phosphorylated O-polysaccharide was isolated from the lipopolysaccharide of an entomopathogenic bacterium Photorhabdus temperata subsp. cinerea 3240 and studied by sugar analysis, dephosphorylation, and (1)H and (13)C NMR spectroscopy. The following structure of the linear trisaccharide repeating unit of the O-polysaccharide was established: →3)-β-D-GalpNAc4PEtN-(1→4)-β-D-GlcpA-(1→3)-β-D-FucpNAc4N-(1→ where GlcA indicates glucuronic acid, FucNAc4N 2-acetamido-4-amino-2,4,6-trideoxygalactose, and PEtN 2-aminoethyl phosphate.

Structure and gene cluster of the O-antigen of Escherichia coli O140

An acidic O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of Escherichia coli O140 and studied by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. The following structure of the branched hexasaccharide repeating unit was established: [Formula: see text]. The O-antigen gene cluster of E. coli O140 was sequenced. The gene functions were tentatively assigned by a comparison with sequences in the available databases and found to be in full agreement with the E. coli O140 polysaccharide structure.

Structure of the O-polysaccharide of the lipopolysaccharide of Pseudomonas chlororaphis subsp. aureofaciens UCM B-306

Structure of the O-specific polysaccharide from Pseudomonas chlororaphis subsp. aureofaciens UCM B-306 was elucidated by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. The polysaccharide is built up of trisaccharide repeats containing D-rhamnose, 2,4-diacetamido-2,4,6-trideoxy-D-glucose (D-QuiNAc4NAc), and 2-acetamido-2-deoxy-D-galacturonic acid (D-GalNAcA), which is amidated in ∼40% repeats. It was suggested that the O-polysaccharide has a blockwise structure, which can be presented as follows: -[→3)-α-D-Rhap-(1→4)-α-D-GalpNAcA-(1→3)-α-D-QuipNAc4NAc-(1-]n→ and -[→3)-α-D-Rhap-(1→4)-α-D-GalpNAcAN-(1→3)-α-D-QuipNAc4NAc-(1-]m→, where GalNAcAN indicates 2-acetamido-2-deoxy-D-galacturonamide, n:m=∼3:2.

Structures and gene clusters of the closely related O-antigens of Escherichia coli O46 and O134, both containing D-glucuronoyl-D-allothreonine

The O-polysaccharides (O-antigens) were isolated by mild acid degradation of the lipopolysaccharide (LPS) of Escherichia coli O46 and O134. The structures of their linear tetrasaccharide repeating units were established by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy: [Formula: see text], where D-aThr indicates D-allothreonine and R indicates O-acetyl substitution (∼ 70% on aThr and ∼ 15% on GalNAc) in E. coli O46 whereas the O-acetylation is absent in E. coli O134. Functions of genes in the essentially identical O-antigen gene clusters of E. coli O46 and O134 were tentatively assigned by a comparison with sequences in available databases and found to be in agreement with the O-polysaccharide structures established.

Classification of a Proteus penneri clinical isolate with a unique O-antigen structure to a new Proteus serogroup, O80

Proteus penneri is an opportunistic pathogen, which may cause severe diseases, most frequently urinary tract infections in immunocompromised patients. P. penneri Br 114 exhibiting a good swarming growth ability as an S-form strain was isolated from a wound of a patient in Łódź, Poland. Serological studies using ELISA and Western blotting and chemical analyses along with (1)H and (13)C NMR spectroscopy showed that the O-antigen (O-polysaccharide) of this strain is unique among the known Proteus serotypes O1-O79. It possesses a linear pentasaccharide repeating unit containing a partially O-acetylated amide of D-glucuronic acid (GlcA) with L-serine having the following structure: [structure: see text]. These data are a basis for creating a new Proteus serogroup, O80, so far represented by the single Br 114 isolate. The O80 is the 21st O-serogroup containing P. penneri strains and the fourth serogroup based on Proteus spp. clinical isolates from Łódź, Poland.

Structure of the O-polysaccharide of Photorhabdus temperata subsp. temperata XlNach(T) containing a novel branched monosaccharide, 3,6-dideoxy-4-C-[(S)-1,2-dihydroxyethyl]-d-xylo-hexose

O-Polysaccharide was isolated from the lipopolysaccharide of an entomopathogenic bacterium Photorhabdus temperata subsp. temperata XlNach(T). Sugar analysis after full acid hydrolysis of the polysaccharide revealed D-glucose, D-mannose, D-galactose, D-GalNAc, and a branched monosaccharide, 3,6-dideoxy-4-C-[(S)-1',2'-dihydroxyethyl]-D-xylo-hexose (Sug), which was isolated as a 1,2'-anhydro furanose derivative. The following structure of the polysaccharide was established by 1D and 2D 1H and 13C NMR spectroscopy: