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The O-specific polysaccharide of Citrobacter braakii PCM1531 (serogroup O6) was isolated by mild acid hydrolysis of the lipopolysaccharide (LPS) and found to contain d-fucose, l-rhamnose, 4-deoxy-d-arabino-hexose and O-acetyl groups in molar ratios 2 : 1 : 1 : 1. On the basis of methylation analysis and 1H and 13C NMR spectroscopy data, the structure of the branched tetrasaccharide repeating unit of the O-specific polysaccharide was established. Using various serological assays, it was demonstrated that the LPS of strain PCM1531 is not related serologically to other known 4-deoxy-d-arabino-hexose-containing LPS from Citrobacter PCM1487 (serogroup O5) or C. youngae PCM1488 (serogroup O36). Two other strains of Citrobacter, PCM1504 and PCM1505, which, together with strain PCM1531, have been classified in serogroup O6, were shown to be serologically distinct from strain PCM1531 and should be reclassified into another serogroup.

Lipopolysaccharide, structure, structural, polysaccharide, O-specific, O-specific polysaccharide, serological, serogroup, serological specificity, O-antigen structure, Citrobacter, Citrobacter braakii, 4-deoxy-D-arabino-hexose

NCBI PubMed ID: 12823543
Journal NLM ID: 0107600
Publisher: Oxford, UK: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Correspondence: katzenel@immuno.iitd.pan.wroc.pl
Institutions: L.Hirszfeld Institute of Immunology and Experimental Therapy, Wroclaw, Poland
Methods: methylation, NMR

No abstract available

synthesis, deoxy sugars

NCBI PubMed ID: 17931551
Publication DOI: 10.1016/S0065-2318(07)61004-X
Journal NLM ID: 0240537
Institutions: CIHIDECAR, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina
Methods: 13C NMR, 1H NMR, NMR-2D, MS, composition analysis, NMR-1D

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

Franconibacter (Enterobacter, Cronobacter) pulveris bacteria share several typical characteristics with, and hence pose a challenge for the detection of, Cronobacter sakazakii, an emerging opportunistic pathogen, which can cause severe infections in neonates. A structurally variable O-specific polysaccharide (OPS) called O antigen provides the major basis for the typing of Gram-negative bacteria. We investigated the structure and genetics of the O antigen of F. pulveris G3872 (designated O1). An OPS was isolated by mild alkaline degradation of the LPS, whereas the same polysaccharide and its oligosaccharide fragments were obtained by mild acid degradation. Studies by sugar analysis and NMR spectroscopy showed that the OPS contained d-ribose, l-rhamnose (l-Rha) and a rarely occurring monosaccharide 4-deoxy-d-arabino-hexose, and the OPS structure was established. The O-antigen gene cluster of F. pulveris G3872 between JUMPStart and gnd genes includes putative genes for glycosyltransferases, ATP-binding cassette (ABC)-transporter genes wzm and wzt, and genes for the synthesis of l-Rha, but no genes for the synthesis of 4-deoxy-d-arabino-hexose. A mutation test with the wzm gene confirmed that the OPS is synthesized and exported by the ABC-transporter-dependent pathway. A trifunctional transferase was suggested to catalyse formation of two glycosidic linkages and add a methyl group to the non-reducing end of the OPS to terminate the chain elongation. A carbohydrate-binding module that presumably recognizes the terminal methyl-modified monosaccharide was found at the C-terminus of Wzt. Primers specific for F. pulveris G3872 were designed based on the wzm gene, which has potential to be used for identification and detection of the O1 serogroup.

Lipopolysaccharide, O-antigen, ABC transporter, Molecular typing, 4-deoxy-D-arabino-hexose, Franconibacter pulveris

NCBI PubMed ID: 27166227
Publication DOI: 10.1099/mic.0.000307
Journal NLM ID: 0376646
Publisher: Washington, DC: Kluwer Academic/Plenum Publishers
Correspondence: Yuriy A. Knirel
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, TEDA School of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China, Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, 300071 Tianjin, China
Methods: 13C NMR, 1H NMR, NMR-2D, PCR, DNA sequencing, SDS-PAGE, sugar analysis, DNA techniques, GLC, mild alkaline degradation, HPLC, GPC, function analysis of gene clusters