O-antigen repeat

Synthesis of Shigella flexneri O-Antigenic Repeating Units... 

Abstract Lipopolysaccharides are the major components on the surface of most Gram-negative bacteria, and recognized by immune cells as a pathogen-associated molecule. They can cause severe diseases like sepsis and therefore known as endotoxins. Lipopolysaccharide consists of lipid A, core oligosaccharide and O-antigen repeats. Lipid A is responsible for the major bioactivity of endotoxin. Because of their specific structure and amphipathic property, purification and analysis of lipopolysaccharides are difficult. In this chapter, we summarize the available approaches for extraction, purification and analysis of lipopolysaccharides. 

Pieretti, G., Corsaro, M.M., Lanzetta, R., Parrilli, M., Vilches, S., Merino, S., Tomas, J.M. Stmctural characterization of the core region of the lipopolysaccharide from the haloalkaliphilic Halomonas pantelleriensis identification of the biological O-antigen repeating. Unit Eur J Org Chem (2009) 1365-1371. 

Scheme 34 Structure o1 Escherichia coli 0128 B12 O-antigen repeating unit. WbsJ at, 2-fucosyitransferase.

Kowal P, Wang PG. A new UDP-GlcNAc C4 epimerase involved in the biosynthesis of 2-acetamino-2-deoxy-L-altruronic acid in the O-antigen repeating units of Plesiomonas shigelloides 017. Biochemistry 2002 41 15410-15414. 

Figure 3.9 Lipopolysaccharide Assembly. Construction of the O-antigen repeating unit in Salmonella,...

Some of the earliest studies of Man-Ts were on polyprenol-P-Man made by Micrococcus lysodeikticus [11]. Other well-studied molecules are the O-antigen repeats of the lipopolysaccharide (EPS) of the outer membrane of Gram-negative bacteria [12], exopolysaccharides such as xanthan [13], and the lipoarabinomannan of the mycobacterial cell envelope [14]. At least one archaeon, Thermoplasma acidophilum, makes a protein-linked glycan containing al,2-, al,3-, and al,6-linked Man [15]. 

The lipopolysaccharide molecule can be divided into three distinct domains the lipid A region, the core sugars, and the O-antigen repeat. Figure IB shows a schematic representation of the LPS molecule. 

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