Structural and serological studies of the related O-specific polysaccharides of Proteus vulgaris O21 and Proteus mirabilis O48 having oligosaccharide-phosphate repeating units

The O-specific polysaccharide chains (O-antigens) of the lipopolysaccharide s (LPSs) of Proteus mirabilis O48 and Proteus vulgaris O21 were found to ha ve tetrasaccharide and pentasaccharide repeating units, respectively, inter linked by a glycosidic phosphate. Polysaccharides and an oligosaccharide we re derived from the LPSs by various degradation procedures and studied by H -1 and C-13 NMR spectroscopy, including 2D COSY, TOCSY, NOESY, H-detected H -1,C-13 and H-1,P-31 HMQC experiments. The following related structures of the repeating units of the O-antigens were established (top: Proteus mirabi lis O48; bottom: Proteus vulgaris O21) [GRAPHICS] The O-specific polysaccharide of P. vulgaris O21 has the same structure as that of Hafnia allvei 744 and PCM 1194 [Petersson C., Jachymek, W., Klonows ka, A., Lugowski, C., Niedziela, T. & Kenne, L. (1997) Eur. J. Biochem., 24 5, 668-675], except that the GlcN residue carries the N-acetyl rather than the N-[(R)-3-hydroxybutyryl] group. Serological investigations confirmed th e close relatedness of the Proteus and Hafnia O-antigens studied.