In vivo determination of Neisseria meningitidis serogroup A capsular polysaccharide by whole cell high-resolution magic angle spinning NMR spectroscopy

High resolution-magic angle spinning (HRMAS) NMR spectroscopy was applied to serogroup A Neisseria meningitidis (NMA) to determine precise structures of capsular polysaccharide (CPS) expressed on the meningococcal surface. Both the O-acetylated (OAc) NMA parent and a mynC::ophA3 OAc- mutant demonstrated characteristic CPS-derived NMR signals indicating cell-surface expression of CPS, but only the parent expressed 0-3 and 0-4 acetylation signals. A capsule-defective strain showed no NMR signals for CPS. The H-1 NMR HRMAS spectral patterns correlated with the purified CPS H-1 NMR profiles. HRMAS NMR can distinguish detailed complex carbohydrate structures expressed on bacteria. NMA express both 0-3 and 0-4 acetylated polymers but not in equimolar ratio amounts in vivo. (c) 2005 Elsevier Ltd. All rights reserved.