Vibrio vulnificus is a pathogenic gram-negative bacterium, endemic to brackish waters, which is often isolated from sediments, from the water column or from shellfish. It is associated with wound infections and septicemia in humans and the virulence of V. vulnificus has been strongly associated with encapsulation. The capsular polysaccharide purified from a virulent strain of V. vulnificus 6353 did not show cross reactivity with antibodies to the capsular polysaccharide of a related pathogenic strain of V. vulnificus (MO6-24) the structure of which was recently reported. NMR spectroscopic analysis of the purified polysaccharide from strain 6353 showed that the polymer is composed of four sugar residues per repeating subunit including 2,6-dideoxy-2-N-acetylamino-α-D-glucose (QuiNAc), 2-deoxy-2-N-acetylamino-α-D-galactose (α-D-GalNAc), 2-deoxy-2-N-acetylamino-α-D-galcturonic acid (α-D-GalNAcA) and 2-N-acetylamino-α-D-glucuronamide (α-D-GlcNAcANH2). The 1H- and 13C NMR spectra were completely assigned by homonuclear and heteronuclear NMR spectroscopy. Sugar types and anomeric configurations were determined from proton homonuclear coupling constants and glycosidic linkages were determined from 1H-13C heteronuclear multiple bond correlation spectra. Sugar identities were confirmed by high performance anion-exchange chromatography and absolute configurations were determined by gas chromatography in combination with molecular modeling and NMR spectroscopy. The structure of the polysaccharide repeating unit is: [→4)-α-D-GalpNAc-(1→3)-α-D-GalpNAcA-(1→3)-α-D-QuipNAc-(1→]n α-D-GlcpNAcANH2(1→4)-→. While there are some common features shared among the structures of the capsular polysaccharides of pathogenic strains of V. vulnificus, there are distinct differences in the detailed structures.
NMR, structure, polysaccharide, bacteria, Vibrio, Vibrio vulnificus
NCBI PubMed ID: 9692929Publication DOI: 10.1046/j.1432-1327.1998.2550279.xJournal NLM ID: 0107600Publisher: Oxford, UK: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Correspondence: bush@umbc.edu
Institutions: Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore MD, USA, Departments of Medicine and Pathology, University of Maryland School of Medicine and Veterans Affairs Medical Center, Baltimore MD, USA
Methods: 13C NMR, 1H NMR, NMR-2D, HPLC
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