Structures of new acidic O-specific polysaccharides of the bacterium Proteus mirabilis serogroups O26 and O30

The polysaccharide chains of the lipopolysaccharides of the Proteus mirabilis serogroups O26 and O30 were studied using sugar and methylation analysis and 1H and 13C NMR spectroscopy, including two-dimensional correlation spectroscopy and rotating-frame NOE spectroscopy. The polysaccharides were found to be acidic due to the presence of d-galacturonic acid and its amide with l-lysine in serogroup O26 or d-glucuronic acid in serogroup O30, and the structures of their tetrasaccharide repeating units were established. The O26-specific polysaccharide is structurally and serologically related to the O-specific polysaccharide of P. mirabilis O28, which includes amides of d-GalA with l-lysine and l-serine [Radziejewska-Lebrecht, J. et al. (1995) Eur. J. Biochem. 230, 705–712].