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The serotyping of O and H antigens is an important first step in the characterization of Salmonella enterica. However, serotyping has become increasingly technically demanding and expensive to perform. We have therefore sequenced additional S. enterica O antigen gene clusters to provide information for the development of DNA-based serotyping methods. Three S. enterica isolates had O antigen gene clusters with homology to the Escherichia coli O123 O antigen region. O antigen clusters from two serogroup O58 S. enterica strains had approximately 85 % identity with the E. coli O123 O antigen region over their entire length, suggesting that these Salmonella and E. coli O antigen regions evolved from a common ancestor. The O antigen cluster of a Salmonella serogroup O41 isolate had a lower level of identity with E. coli O123 over only part of its O antigen DNA cluster sequence, suggesting a different and more complex evolution of this gene cluster than those in the O58 strains. A large part of the Salmonella O41 O antigen DNA cluster had very close identity with the O antigen cluster of an O62 strain. This region of DNA homology included the wzx and wzy genes. Therefore, molecular serotyping tests using only the O41 or O62 wzx and wzy genes would not differentiate between the two serogroups. The E. coli O123 O-antigenic polysaccharide and its repeating unit were characterized, and the chemical structure for E. coli O123 was entirely consistent with the O antigen gene cluster sequences of E. coli O123 and the Salmonella O58 isolates. An understanding of both the genetic and structural composition of Salmonella and E. coli O antigens is necessary for the development of novel molecular methods for serotyping these organisms

structure, O-antigen, serogroup, Salmonella enterica, serotyping

NCBI PubMed ID: 19502376
Journal NLM ID: 0224131
Publisher: Reading, England: Society for General Microbiology
Correspondence: clifford_clark@phac-aspc.gc.ca
Institutions: Enteric Diseases Program, Bacteriology and Enteric Diseases Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R3E 3R2, Canada
Methods: 13C NMR, 1H NMR, methylation, GLC-MS, NMR-2D, composition analysis, serological methods, genetic methods

O-Polysaccharides were isolated by mild acid degradation of the lipopolysaccharides of Escherichia coli O123 and Salmonella enterica O58 and studied by chemical methods and 2D (1)H and (13)C NMR spectroscopy, including experiments in a H(2)O/D(2)O mixture, which enabled observation of correlations for nitrogen-linked protons. The following structure of the O-polysaccharide of E. coli O123 was established: →3)-β-D-Quip4NAlaHb-(1→6)-α-D-GlcpNAc-(1→3)-α-L-QuipNAc-(1→3)-α-D-Glcp (6)(approx. 30% OAc)NAc-(1→ where L-QuipNAc stands for 2-acetamido-2,6-dideoxy-L-glucose and D-Qui4NAlaHb for 4-{N-[(S)-3-hydroxybutanoyl]-D-alanyl}amino-4,6-dideoxy-D-glucose. The latter was isolated as an ethylene glycol glycoside by three sequential Smith degradations of the O-deacetylated O-polysaccharide. The structure established in this work is at variance with the E. coli O123-polysaccharide structure reported earlier [Clark, C. G.; Kropinski, A. M.; Parolis, H.; Grant, C. C.; Trout-Yakel, K. M.; Franklin, K.; Ng, L. K.; Paramonov, N. A.; Parolis, L. A.; Rahn, K.; Tabor, H. J. Med. Microbiol.2009, 58, 884-894]. In accordance with the genetic data, the O-polysaccharide of S. enterica O58 has the same structure, except for it lacks the O-acetylation.

O-antigen, Escherichia coli, Salmonella enterica, 6-dideoxy-d-glucose, 4-amino-4, O-Polysaccharide structure, Smith degradation

NCBI PubMed ID: 20181329
Publication DOI: 10.1016/j.carres.2010.01.019
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: A.V. Perepelov
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
Methods: 13C NMR, 1H NMR, NMR-2D, ESI-MS, GLC, mild acid hydrolysis, Smith degradation, de-O-acetylation, composition analysis, NMR-1D

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.

Lipopolysaccharide, O-antigen, Escherichia coli, bacterial polysaccharide structure, O-antigen gene cluster

Publication DOI: 10.1016/j.carres.2016.09.014
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: yknirel@gmail.com
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
Methods: 13C NMR, 1H NMR, NMR-2D, sugar analysis, GLC, Smith degradation, GPC, mild acid degradation, function analysis of gene clusters

Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and four (O14, O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.

structure, O antigen, Escherichia coli, gene cluster, serogroup, diversity

NCBI PubMed ID: 31778182
Publication DOI: 10.1093/femsre/fuz028
Journal NLM ID: 8902526
Publisher: Oxford University Press
Correspondence: G. Widmalm ; Lei Wang
Institutions: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden, N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, China, The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, China, School of Molecular and Microbial Bioscience (G08), University of Sydney, Sydney, Australia, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China, Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China

To understand the role of human natural IgM known as antibodies against the carbohydrate epitope Tn, the antibodies were isolated using GalNAcα-Sepharose affinity chromatography, and their specificity was profiled using microarrays (a glycan array printed with oligosaccharides and bacterial polysaccharides, as well as a glycopeptide array), flow cytometry, and inhibition ELISA. The antibodies bound a restricted number of GalNAcα-terminated oligosaccharides better than the parent monosaccharide, e.g., 6-O-Su-GalNAcα and GalNAcα1-3Galβ1-3(4)GlcNAcβ. The binding with several bacterial polysaccharides that have no structural resemblance to the affinity ligand GalNAcα was quite unexpected. Given that GalNAcα is considered the key fragment of the Tn antigen, it is surprising that these antibodies bind weakly GalNAcα-OSer and do not bind a wide variety of GalNAcα-OSer/Thr-containing mucin glycopeptides. At the same time, we have observed specific binding to cells having Tn-positive glycoproteins containing similar glycopeptide motifs in a conformationally rigid macromolecule. Thus, specific recognition of the Tn antigen apparently requires that the naturally occurring "anti-Tn" IgM recognize a complex epitope comprising the GalNAcα as an essential component and a fairly long amino acid sequence where the amino acids adjacent to GalNAcα do not contact the antibody paratope; i.e., the antibodies recognize a spatial epitope or a molecular pattern rather than a classical continuous sequence. In addition, we have not found any increase in the binding of natural antibodies when GalNAcα residues were clustered. These results may help in further development of anticancer vaccines based on synthetic Tn constructs.

cancer, glycans, natural antibodies, anti-glycan antibodies, Tn antigen

NCBI PubMed ID: 32087569
Publication DOI: 10.1016/j.molimm.2020.02.005
Journal NLM ID: 7905289
Publisher: Elsevier
Correspondence: professorbovin@yandex.ru
Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya, Moscow, Russian Federation, Semiotik LLC, 16/10 Miklukho-Maklaya, Moscow, Russian Federation, National Medical Research Center for Obstetrics, Gynecology and Perinatology Named after Academician V.I. Kulakov of the Ministry of Healthcare of Russian Federation, Moscow, Russian Federation, National Research University Higher School of Economics, Moscow, Russian Federation, Department of Chemistry, Chemical Biology, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark, Institut Fur Organische Chemie, Johannes Gutenberg-Universitat Mainz, Duesbergweg 10-14, D-55128, Mainz, Germany, Institute of Immunology, Federal Medical-Biological Agency of Russia, Moscow, Russian Federation, University of Nantes, Inserm, U892 IRT UN, 8 Quai MonCousu, BP70721 Nantes, FR 44007, France
Methods: ELISA, affinity chromatography, flow cytometry analysis, printed glycan array (PGA) analysis, FACS assay