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Structure of a muramic acid containing capsular polysaccharide from the pathogenic strain of Vibrio vulnificus ATCC
S Gunawardena1, G P Reddy, Y Wang
1Department of Chemistry and Biochemistry, University of Maryland Baltimore County 21250, USA.
Abstract:
Vibrio vulnificus strains isolated from septicemia cases and from the environment show a wide variety of capsular types. In an attempt to find common structural features which can be correlated with pathogenicity and toxicity, we have determined structures of the capsular polysaccharides (CPS) from several pathogenic strains. We report the complete structure of the polysaccharide from the pathogenic V. vulnificus strain ATCC 27562 using a combination of homonuclear and heteronuclear one-dimensional and two dimensional NMR experiments. The 13C and 1H NMR spectra, including the exchangeable amide proton resonances, have been completely assigned. The amide linkage between Ser and C6 of GalA has been unambiguously determined by water-suppressed 2D NOESY. To verify the structure established by NMR, we have fragmented the polymer employing the Smith degradation procedure. The Smith product identified by NMR and matrix-assisted laser desorption mass spectrometry is consistent with the proposed structure for the CPS, which is composed of D-GlcNAc, MurNAc, D-GalA, L-Rha and is serine-linked as shown: [formula: see text]
Insights
Researchers elucidated the capsular polysaccharide structure of the pathogenic Vibrio vulnificus strain ATCC 27562. This finding aids in understanding the common structural features linked to pathogenicity and toxicity in Vibrio vulnificus.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Vibrio vulnificus strains exhibit diverse capsular types, complicating pathogenicity and toxicity correlations.
- Understanding capsular polysaccharide (CPS) structures is crucial for identifying virulence factors.
Purpose of the Study:
- To determine the complete structure of the CPS from the pathogenic V. vulnificus strain ATCC 27562.
- To identify common structural features of CPS that may correlate with pathogenicity and toxicity.
Main Methods:
- Utilized a combination of homonuclear and heteronuclear one-dimensional and two-dimensional NMR spectroscopy.
- Employed Smith degradation to fragment the polymer for structural verification.
- Analyzed Smith degradation products using NMR and matrix-assisted laser desorption mass spectrometry.
Main Results:
- The complete structure of the CPS from V. vulnificus ATCC 27562 was elucidated.
- The CPS is composed of D-GlcNAc, MurNAc, D-GalA, and L-Rha.
- An unambiguous serine linkage to C6 of GalA was determined using 2D NOESY.
Conclusions:
- The determined CPS structure provides a basis for understanding Vibrio vulnificus pathogenicity.
- Structural characterization of CPS is essential for correlating features with virulence and toxicity.