Lipopolysaccharide (LPS) is the major component of the outer leaflet of the outer membrane of Gram-negative bacteria. The LPS molecule is composed of two biosynthetic entities: the lipid A - core and the O-polysaccharide (O-antigen). Most biological effects of LPS are due to the lipid A part, however, there is an increasing body of evidence indicating that O-antigen (O-ag) plays an important role in effective colonization of host tissues, resistance to complement-mediated killing and in the resistance to cationic antimicrobial peptides that are key elements of the innate immune system.

Recently, data has started to accumulate on the intricacies in the genetic regulation of the structural components of this molecule and this is highly relevant to the biological function of the molecule.

from Skurnik M and Bengoechea JA in Bacterial Polysaccharides: Current Innovations and Future Trends (2009) Ullrich M (Ed) Published by Caister Academic Press

Further reading: Bacterial Polysaccharides

Labels: gram negative bacteria, lipopolysaccharide, LPS, pathogenesis, polysaccharides, regulation