5 - Teichoic Acids of Gram-positive Bacteria

Abstract

Teichoic acids are fairly short linear polymers, usually with a chain length of 30–40 repeating units. They exhibit a diversity of regular repeating polymeric structures in which the common feature is the linkage of the repeating units through phosphodiesters. The simplest types are those in which the repeating unit is a simple alditol phosphate: glycerol phosphate, erythritol phosphate, ribitol phosphate, or mannitol phosphate or a sugar-1-phosphate. Of these, the glycerol phosphate and ribitol phosphate types are the most widely distributed amongst bacterial species. They frequently bear glycosyl substituents on one of the hydroxyls of the alditol. Other teichoic acids contain more complex repeating units in which a sugar, oligosaccharide or sugar-l-phosphate, linked to an alditol phosphate, constitutes part of the main polymer chain. Teichoic acids are quantitatively important constituents of Gram-positive cell walls. In many bacteria, they constitute up to 50% of the weight of the cell wall and contain as much as 40% of total cell phosphorus. In such cases, approximately 10% of all muramic acid residues throughout the peptidoglycan network of the cell wall bear a teichoic acid chain. In Bacillus subtilis, teichoic acid is not synthesized constitutively and during phosphate-limited growth its synthesis is rapidly inactivated. Cell wall teichoic acids are important surface antigens in several pathogenic species. The ribitol teichoic acid (RTA) of Staph. aureus is the major immunological determinant of that species and antibodies generally exhibit specificity for the anomeric configuration of the N-acetylglucosaminyl substituents on the polymer.