Elucidation of the structure of the oligosaccharide from wild type Moraxella bovis Epp63 lipooligosaccharide

Abstract

Moraxella bovis is a Gram-negative microorganism that causes Infectious Bovine Keratoconjunctivitis (IBK), colloquially known as ‘Pink eye’ in cattle worldwide. Lipopolysaccharides/lipooligosaccharides are the predominant glycans on the surface of Gram-negative microorganisms. Structural elucidation of the oligosaccharide structure of the rough phenotype of Moraxella bovis strain Epp63 was determined using GC–MS, methylation analysis, and NMR spectroscopy. The oligosaccharide is a branched structure that comprises 10 sugars in addition to KDO. The unusual features of this oligosaccharide include the fact that the oligosaccharide is devoid of heptose. The KDO residue is directly attached to a (→4,6)-branched glucose and additionally contains a terminal open chain acetal-linked N-acetylgalactosamine, (1S)-GalaNAc residue →4,6-linked to a sub-terminal galactose residue.