Structure of Lipopolysaccharide Endotoxins
Our last blog on endotoxins is about the importance of endotoxins in general. Here, we introduce the structure of one of the best investigated endotoxins - lipopolysaccharide (LPS). LPS occurs only in the cell wall of Gram-negative not Gram-positive bacteria, respectively. It contributes to the structural integrity of the bacteria and provides protection against environmental conditions like salts, lipophilic antibiotics and many more.1 Molecularly, LPS consists of the hydrophobic, highly conserved lipid A, the hydrophilic core polysaccharide components (core) and the highly variable O-specific polysaccharide side chain (Figure 1). In most cases, the O-responsible side chain is made up of repetitive oligosaccharide units that lead to strain specific structural diversity. The different strain specific O serotype is determined by the organization and interconnection of the oligosaccharide units. In this way the O serotype is the main criterion for the serotyping classification of Salmonella. Evolutionarily, the various O-Serotypes of the Enterobacteriaceae have developed to escape the host's immune system by varying the surface structure of the bacteria. By displaying LPS on the bacterial surface it acts as an antigen and is also known as O-antigen.2 Figure 1. General structure of LPS. Read the full article