Teichoic acid

Structure of a teichoic acid from Micrococcaceae

Teichoic acids (cf. Greek τειχος, teichos, "wall") are bacterial polysaccharides^[1] of glycerol phosphate or ribitol phospate linked via phosphodiester bonds.

Location and structure

These acids can be found in the cell wall of gram-positive bacteria, such as Staphylococci, Streptococci, Bacillus, Clostridium, Corynebacterium and Listeria, and appear to extend to the surface of the peptidoglycan layer. Teichoic acids are not found in the gram-negative bacteria. They can be either covalently bonded to N-acetylmuramic acid of the peptidoglycan layer, linked to the plasma membrane lipids found in the cytoplasmic membrane, or linked to a terminal D-alanine in the tetrapeptide cross-links between molecules of N-acetylmuramic acid. The combined units comprising teichoic acids and lipids are referred to as lipoteichoic acids.

Function

The main function of teichoic acids is to provide rigidity to the cell-wall by attracting cations such as Magnesium and Sodium. Teichoic acids are usually, but not always, substituted with d-alanine ester residues,^[2] giving the molecule zwitterionic properties.^{[citation needed]} These zwitterionic teichoic acids are suspected ligands for toll-like receptors 2 and 4.^{[citation needed]} Teichoic acids also assist in regulation of cell growth by limiting the ability of autolysins to break the β(1-4) bond between the N-acetyl glucosamine and the N-acetylmuramic acid.^{[citation needed]}

Teichoic acids serve as an attachment site for some parasites. Destruction of the bacteria and release of the Teichoic acid into the bloodstream may cause fever, blood vessel dilation and possibly shock and subsequent death. Teichoic acid can also be used by bacteria to attach to mucosal membranes.

See also

• Lipoteichoic acid - a major constituent of the cell wall of gram positive bacteria

References

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