Bacteria LPS

LPS is a constituent of the outer membrane of the cell wall of certain types of Gram-negative bacteria, such as E. coli, Salmonella, Shigella, Pseudomonas, Neisseria, Haemophilus, and some other lesser known pathogens. The endotoxins of Gram-negative bacteria are LPS molecules with three distinct domains referred to as lipid A, core oligosaccharide and O-polysaccharide. The lipid A and core oligosaccharide comprise the endotoxin core and are relatively conserved among different Gram-negative bacterial species. The O-polysaccharides show wide structural diversity and give rise to the O-specificity of different strain and species serotypes. Lipid A is the toxic moiety of endotoxin, and is covalently linked to core oligosaccharide in all LPS. Rough (R) bacteria lack the O-polysaccharide of their smooth (S) strain bacteria counterparts, and different rough mutant bacteria have been isolated expressing a range of incomplete core oligosaccharide structures ranging from complete core (Ra) to deep-rough (Re) mutants expressing only lipid A linked to inner-core KDO residues.