Endotoxins: Lipopolysaccharides of Gram-Negative Bacteria

Part of the Subcellular Biochemistry book series (SCBI, volume 53)


Endotoxin refers lipopolysaccharide that constitutes the outer leaflet of the outer membrane of most Gram-negative bacteria. Lipopolysaccharide is comprised of a hydrophilic polysaccharide and a hydrophobic component known as lipid A which is responsible for the major bioactivity of endotoxin. Lipopolysaccharide can be recognized by immune cells as a pathogen-associated molecule through Toll-like receptor 4. Most enzymes and genes related to the biosynthesis and export of lipopolysaccharide have been identified in Escherichia coli, and they are shared by most Gram-negative bacteria based on available genetic information. However, the detailed structure of lipopolysaccharide differs from one bacterium to another, suggesting that additional enzymes that can modify the basic structure of lipopolysaccharide exist in bacteria, especially some pathogens. These structural modifications of lipopolysaccharide are sometimes tightly regulated. They are not required for survival but closely related to the virulence of bacteria. In this chapter we will focus on the mechanism of biosynthesis and export of lipopolysaccharide in bacteria.


Outer membrane Lipopolysaccharide Endotoxin Lipid A LPS biosynthesis 





Toll-like receptor 4


3-deoxy-d-manno-octulosonic acid




cationic antimicrobial peptides




undecaprenyl phosphate-l-Ara4N

galacturonic acid




Funding was provided by grants from the National Natural Science Foundation of China (NSFC 30770114, NSFC30870074), the Program of State Key Laboratory of Food Science and Technology (SKLF-MB-200801), the 111 project (111-2-06), the Basic Research Programs of Jiangsu Province (BK2009003), and the Human Science Frontier Programme (RGP0016/2005C).


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© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.State Key Laboratory of Food Science and TechnologyJiangnan UniversityWuxiChina
  2. 2.Department of BiochemistryKing’s College LondonLondonUK

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