Structural and genetic characterization of the O-antigen of Salmonella enterica O56 containing a novel derivative of 4-amino-4,6-dideoxy-d-glucose Original Research Article

Based on the O-antigens (O-polysaccharides), one of the most variable cell constituents, 46 O-serogroups have been recognized in the Kauffmann–White serotyping scheme for Salmonella enterica. In this work, the structure of the O-polysaccharide and the genetic organization of the O-antigen gene cluster of S. enterica O56 were investigated. As judged by sugar and methylation analyses, along with NMR spectroscopic data, the O-polysaccharide has a linear tetrasaccharide O-unit, which consists of one residue each of d-ribofuranose, N-acetyl-d-glucosamine, N-acetyl-d-galactosamine, and a novel sugar derivative, 4-(N-acetyl-l-seryl)amino-4,6-dideoxy-d-glucose (d-Qui4NSerAc). The following structure of the O-polysaccharide was established: