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A polysaccharide containing D-galactose (Gal), 2-acetamido-2-deoxy-D-galactose (GalNAc), 2-acetamido-2-deoxy-D-glucose (GlcNAc), and 3-deoxy-3-(D-3-hydroxybutyramido)-D-quinovose (Qui3NR) was isolated from lipopolysaccharide (LPS) obtained from cells walls of the reference strain for Acinetobacter baumannii O23. By means of NMR studies, methylation analysis, and chemical degradations, the repeating unit of the polymer was identified as a branched pentasaccharide with the structure 1. The same polymer was apparently also present in LPS of the reference strain for serogroup O12, together with a second polymer based on a branched tetrasaccharide with the structure 2. This second polymer has previously been isolated as the O16 antigen of A. baumannii [Haseley, S.R., Diggle, H.J. & Wilkinson, S. G. (1996) Carbohydr. Res. 293, 259-265] and is probably present as a minor component of the LPS of A. baumannii O11 [Haseley, S.R. & Wilkinson, S.G. (1996) Eur. J. Biochem. 237, 266-271]. [Sequence: see text]

Lipopolysaccharide, lipopolysaccharides, LPS, structure, strain, Acinetobacter, Acinetobacter baumannii, O antigens, reference

NCBI PubMed ID: 9063458
Journal NLM ID: 0107600
Publisher: Oxford, UK: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Institutions: School of Chemistry, University of Hull, England, Institute fur Medizinishe Mikrobiologue und Hygiene, Universitat des Saarlandes, Homburg, Germany
Methods: methylation, NMR-2D, partial acid hydrolysis, NMR, Smith degradation, de-N-acylation/deamination

The lipopolysaccharide (LPS) is the major constituent of the outer leaflet of the outer membrane of Gram-negative bacteria. Its lipid A moiety is embedded in the membrane and serves as an anchor for the rest of the LPS molecule. The outermost repetitive glycan region of the LPS is linked to the lipid A through a core oligosaccharide (OS), and is designated as the O-specific polysaccharide (O-polysaccharide, OPS) or O-antigen. The O-antigen is the most variable portion of the LPS and provides serological specificity, which is used for bacterial serotyping. The OPS also provides protection to the microorganisms from host defenses such as complement mediated killing and phagocytosis, and is involved in interactions of bacteria with plants and bacteriophages. Studies of the OPSs ranging from the elucidation of their chemical structures and conformations to their biological and physico-chemical properties help improving classification schemes of Gram-negative bacteria. Furthermore, these studies contributed to a better understanding of the mechanisms of pathogenesis of infectious diseases, as well as provided information to develop novel vaccines and diagnostic reagents.

Lipopolysaccharide, synthesis, lipopolysaccharides, structure, Bacterial, host, O-antigen, O antigen, cell, O antigens, O-antigens, chemical, interaction, cells, PDF, chemical synthesis, biogenesis

Publication DOI: 10.1007/978-3-7091-0733-1_3
Publisher: Springer
Correspondence: knirel@ioc.ac.ru
Editors: Knirel YA, Valvano MA
Institutions: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia

We have sequenced the gene clusters for type strains of the Acinetobacter baumannii serotyping scheme developed in the 1990s, and used the sequences to better understand diversity in surface polysaccharides of the genus. We obtained genome sequences for 27 available serovar type strains, and identified 25 polysaccharide gene cluster sequences. There are structures for 12 of these polysaccharides, and in general the genes present are appropriate to the structure where known. This greatly facilitates interpretation. We also find 53 different glycosyltransferase genes, and for 7 strains can provisionally allocate specific genes to all linkages. We identified primers that will distinguish the 25 sequence forms by PCR or microarray, or alternatively the genes can be used to determine serotype by 'molecular serology'. We applied the latter to 190 Acinetobacter genome-derived gene-clusters, and found 76 that have one of the 25 gene-cluster forms. We also found novel gene clusters and added 52 new gene-cluster sequence forms with different wzy genes and different gene contents. Altogether, the strains that have one of the original 25 sequence forms include 98 A. baumannii (24 from our strains) and 5 A. nosocomialis (3 from our strains), whereas 32 genomes from 12 species other than A. baumannii or A. nosocomialis, all have new sequence forms. One of the 25 serovar type sequences is found to be in European clone I (EC I), 2 are in EC II but none in EC III. The public genome strains add an additional 52 new sequence forms, and also bring the number found in EC I to 5, in EC II to 9 and in EC III to 2.

antigen, structure, Acinetobacter baumannii, gene cluster, glycosyltransferase, serotyping, genome, surface polysaccharide, polysaccharide antigen

NCBI PubMed ID: 23922982
Publication DOI: 10.1371/journal.pone.0070329
Journal NLM ID: 101285081
Publisher: San Francisco, CA: Public Library of Science
Correspondence: Peter R. Reeves
Institutions: TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, China, Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands, School of Molecular Bioscience, University of Sydney, Sydney, Australia
Methods: PCR, DNA sequencing, DNA techniques, genetic methods

The emergence of multidrug-resistance Acinetobacter baumannii requires novel approaches for prevention, treatment and diagnosis. The structures of surface polysaccharides from A. baumannii are valuable tools to understand pathogenesis, virulence and immunogenicity. The synthesis of bacterial mono- or polysaccharides may result in novel probes to become important therapeutic options in the fight against A. baumannii. This report exemplifies the relevance of glycochemistry for the development of new antibiotics.

lipopolysaccharides, capsular polysaccharides, Acinetobacter, Acinetobacter baumannii, polysaccharide synthesis, surface polysaccharides

NCBI PubMed ID: 26531136
Publication DOI: 10.1016/j.carres.2015.10.001
Journal NLM ID: 0043535
Publisher: Elsevier
Correspondence: denis.giguere@chm.ulaval.ca
Institutions: Département de Chimie, Université Laval, Québec City, Québec, Canada G1V 0A6

Bacterial extracellular polysaccharides are known as a cell-bound capsule, a sheath, or a slime, which is excreted into the environment. They play an important role in virulence of medical bacteria and plant-to-symbiont interaction and are used for serotyping of bacteria and production of vaccines. Some exopolysaccharides have commercial applications in industry, and claims of health benefits have been documented for an increasing number of them. Exopolysaccharides have diverse composition and structure, and some contain sugar and non-sugar components that are found in bacterial carbohydrates only. The present article provides an updated collection of the data on exopolysaccharides of various classes of gram-negative and gram-positive bacteria reported until the end of 2019. When known, biosynthesis pathways of exopolysaccharides are treated in a summary manner. References are made to structure and biosynthesis relatedness between exopolysaccharides of different bacterial taxa as well as between bacterial polysaccharides and mammalian glycosaminoglycans.

polysaccharide structure, Gram-negative bacteria, capsule, Biofilm, polysaccharide biosynthesis, gram-positive bacteria, Monosaccharide composition, Bacterial exopolysaccharide, non-sugar component

Publication DOI: 10.1016/B978-0-12-819475-1.00005-5
Publisher: Elsevier
Correspondence: marie-rose.vancalsteren@canada.ca; yknirel@gmail.com
Editors: Barchi J, Kamerling H
Institutions: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada