Structure of the Core Region from the Lipopolysaccharide of Plesiomonas shigelloides Strain 302-73 (Serotype O1)

Plesiomonas shigelloides is a Gram-negative pathogenic bacterium belonging to the Enterobacteriaceae family. To date, only few lipopolysaccharide (LPS) structures from P. shigelloides strains are known. In particular, three core oligosaccharides have been found. Recently, we elucidated the structure of the O-antigen of P. shigelloides 302-73 (serotype O1) and in this paper we present the characterization of the core structure from the LPS of the same strain. The LPS was hydrolyzed under both alkaline and mildly acidic conditions. In both cases, a mixture of oligosaccharides was obtained, which was Purified by get filtration and HPAEC. The oligosaccharides were characterized by chemical analysis, 21) NMR spectroscopy and MALDI-TOF mass spectrometry. A new core structure was found for P shigelloides. In particular, from the analysis of the acid hydrolysed product it was possible to reveal the presence of a Of D-glycero-D-talo-2-octulopyranosonic acid (Ko) residue, which substitutes in part the terminal 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) unit. The Ko residue is not frequently found in core structures. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)