Discuss the role of O antigens in bacterial pathogenicity and host immune responses
The O-antigen part of the LPS also is a complex polysaccharide and is synthesized in the cytoplasmic membrane in two stages.
The repeating sugar units are assembled on the lipid carrier (bactoprenol-P) by stepwise addition of each sugar.
The repeating sugar units are polymerized with the release of one bactoprenol-P for each repeated unit added to the growing chain. This polymerization is thought to occur on the outer face of the cytoplasmic membrane.
This same lipid carrier, bactoprenol-P, is used to synthesize peptidoglycan, LPS, teichoic acids, and capsular polysaccharides. The antibiotic bacitracin forms a complex with bactoprenol-PP and prevents its dephosphorylation, thereby preventing its role as a carrier.