The structure of the rough-type lipopolysaccharide from Shewanella oneidensis MR-1, containing 8-amino-8-deoxy-Kdo and an open-chain form of 2-acetamido-2-deoxy-d-galactose Original Research Article

The LPS from Shewanella oneidensis strain MR-1 was analysed by chemical methods and by NMR spectroscopy and mass spectrometry. The LPS contained no polysaccharide O-chain, and its carbohydrate backbone had the following structure: (1S)-GalNAco-(1→4,6)-α-Gal-(1→6)-α-Gal-(1→3)-α-Gal-(1-P-3)-α-DDHep-(1→5)-α-8-aminoKdo4R-(2→6)-β-GlcN4P-(1→6)-α-GlcN1P, where R is P or EtNPP. There are several novel aspects to this LPS. It contains a novel linking unit between the core polysaccharide and lipid A moieties, namely 8-amino-3,8-dideoxy-d-manno-octulosonic acid (8-aminoKdo) and a residue of 2-acetamido-2-deoxy-d-galactose (N-acetylgalactosamine, GalNAco) in an open-chain form, linked as cyclic acetal to O-4 and O-6 of d-galactopyranose. The structure contains a phosphodiester linkage between the α-d-galactopyranose and d-glycero-d-manno-heptose (DDHep) residues.