Structural analysis of the lipopolysaccharide from Neisseria meningitidis strain BZ157 galE:: localisation of two phosphoethanolamine residues in the inner core oligosaccharide

The structure of the phase-variable lipopolysaccharide (LPS) from the group B Neisseria meningitidis strain BZ157 galE was elucidated. The structural basis for the LPS's variation in reactivity with a monoclonal antibody (MAb) B5 that has specificity for the presence of phosphoethanolamine (PEtn) at the 3-position of the distal heptose residue (HepII) was established. The structure of the O-deacylated LPS was deduced by a combination of monosaccharide analyses, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. These analyses revealed the presence of a novel inner core oligosaccharide (OS) structure in the MAb B5 reactive (B5 +) LPS that contained two PEtn residues simultaneously substituting the 3- and 6-positions of the HepII residue. The determination of this structure has identified a further degree of variability within the inner core OS of meningococcal LPS that could contribute to the interaction of meningococcal strains with their host. (C) 2002 Elsevier Science Ltd. All rights reserved.