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Structure of the O-specific polysaccharide of the bacterium Proteus mirabilis O29
A V Perepelov1, A S Shashkov, S N Senchenkova
1Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 117913, Russia.
Abstract:
An O-specific polysaccharide was obtained by mild acid degradation of P. mirabilis O29 lipopolysaccharide (LPS) and found to contain 2-acetamido-2-deoxy-D-galactose and D-glucuronic acid (D-GlcA) in the ratio 3:1. Studies of the polysaccharide by 1H- and 13C-NMR spectroscopy including two-dimensional correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), and H-detected 1H,13C-heteronuclear multiple-quantum coherence (HMQC) experiments demonstrated the following structure of the branched tetrasaccharide repeating unit:
Insights
Researchers characterized the O-specific polysaccharide from Proteus mirabilis O29 lipopolysaccharide (LPS). Structural analysis revealed a branched tetrasaccharide repeating unit composed of specific sugars.
Area of Science:
- Carbohydrate Chemistry
- Microbial Biochemistry
- Structural Biology
Background:
- Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria, playing critical roles in bacterial structure and host-pathogen interactions.
- The O-specific polysaccharide (O-antigen) of LPS is highly variable and serves as a key determinant of serotype specificity.
- Understanding the structure of O-antigens is crucial for vaccine development and diagnostics.
Purpose of the Study:
- To determine the precise structure of the O-specific polysaccharide derived from Proteus mirabilis O29 lipopolysaccharide (LPS).
- To elucidate the repeating unit structure of the P. mirabilis O29 O-antigen.
Main Methods:
- Mild acid degradation of P. mirabilis O29 LPS to isolate the O-specific polysaccharide.
- Advanced Nuclear Magnetic Resonance (NMR) spectroscopy techniques, including 1H, 13C-NMR, COSY, TOCSY, NOESY, and HMQC, were employed for structural elucidation.
- Analysis of spectroscopic data to determine the composition and linkage of monosaccharide residues.
Main Results:
- The O-specific polysaccharide was found to contain 2-acetamido-2-deoxy-D-galactose and D-glucuronic acid (D-GlcA) in a molar ratio of 3:1.
- Detailed NMR analyses confirmed a branched tetrasaccharide repeating unit structure.
- The specific arrangement and linkages of the monosaccharides within the repeating unit were established.
Conclusions:
- The complete structure of the branched tetrasaccharide repeating unit of the P. mirabilis O29 O-antigen has been elucidated.
- This detailed structural information provides a foundation for further immunological studies and potential applications in diagnostics or therapeutics.