ABSTRACT
The basic structure of the lipopolysaccharide (LPS) core oligosaccharide (OS) of Escherichia coli and Salmonella enterica serovar Typhimurium was elucidated in the 1960s and early 1970s. As structural and analytical methods have advanced, the fine structural details of these core OS have been established. The structure of the core OS is made up of a backbone of 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo), heptose, and hexose sugars. The “smooth” and “rough” terminology originates from observations that colonies of O-polysaccharide (O-PS) containing strains often have a smooth appearance on solid media, whereas colonies of mutants that do not produce an O-PS tend to have a rough surface. Current knowledge of the biosynthesis and genetics of core OS leans heavily on information from E. coli and Salmonella, and for the most part biochemical data are confined to these organisms.
