Teichoic acid

Teichoic acids are polymeric components of the cell wall of gram-positive bacteria and can account for 20-40 % of cell wall dry weight. They are usually covalently to the peptidoglycan ( murein layer ) anchored. Teichoic acids consist of either ribitol -phosphate polymer ( ribitol - teichoic acids ) or glycerol -phosphate polymers ( glycerol teichoic acids ) that protrude like a chain to the outside.

Lipoteichoic acids are referred to as glycerol teichoic acids, which are covalently coupled to the cell membrane glycolipids. These are thus anchored in the cell membrane and penetrate the entire peptidoglycan.

The teichoic practice in the interaction of bacteria with host cells important functions, such as adhesion and as so-called virulence factors.

Lipoteichoic

Lipoteichoic acid (LTA ) are mainly found in gram-positive bacteria, in which the guanine and cytosine content (GC ) content of the DNA is less than 50 %. In gram-positive bacteria with more than 50% GC content can be found mostly Lipoglycane instead of lipoteichoic acids. Lipoteichoic acids are composed of a hydrophilic chain and one amphiphilic Alditolphosphaten glycolipid which functions as a membrane anchor. Staphylococcus aureus is found Polyglycerolphosphat - LTA. This WTA - type is the most common and the species Bacillus, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Listeria, and Streptococcus was also found in genera. The Polyglycerolphosphatkette the LTA of S. aureus is composed of 16-40 1,3 -linked Glycerolphosphateinheiten and linked via a phosphodiester bond to the glycolipid. The Glycerolphosphatreste of most ADs are partially modified with D- alanine esters, and in many bacteria can also find Glycosylsubstituenten. Also in S. aureus can be found D- alanine ester and Glycosylsubstituenten.

The LTA appears to exert important functions in the physiology of the cell wall. Thus, various functions have been proposed, such as the binding of magnesium ions, adhesion to host cells, or the regulation of autolysins. The biosynthesis of LTA seems to be a transmembrane process because all components have lipid character. The composition of the AD begins with a phosphatidyl glycerol Glycerolphospattransfer of the glycolipid, which serves as a lipid anchor, wherein phosphatidylglycerol is used as a chain extender Glycerolphosphatspender. In addition, possibly two glycerophosphate transferases are still involved. One which recognizes the glycolipid and a second which is responsible for the chain extension. For each glycerophosphate which is transmitted, is formed at the inner membrane of a diacylglycerol, which is recycled back to phosphatidylglycerol. Part of diacylglycerol is used to Glycolipidsynthese.

Wandteichonsäuren

Wandteichonsäuren ( WTA ) are localized in the peptidoglycan. Structurally, they are composed of complex compared to the LTA. The anchor structure, which is bound via a phosphodiester bond to the oxygen of the N- acetylmuramic acid of the peptidoglycan is composed of one molecule of N-acetylglucosamine, one molecule of N-acetyl- mannosamine and three molecules of glycerol phosphate. Via modifications of this anchor structure has been reported, however, of the GlcNAc -1-phosphate terminus seems to be the same everywhere. A chain of alternating Alditolphosphaten frequencies is adjacent to the anchor structure that make up the main part of the WTA. The most widespread are chains of glycerol phosphate and Ribitolphosphateinheiten. S. aureus produces a WTA, which is composed of ~ 40 Ribitolphosphateinheiten, whereas other staphylococci have also Glycerolphosphatketten. The Ribitolphosphateinheiten are partially modified by N-acetylglucosamine and D -alanine.

Effect in humans

Teichoic acids and lipoteichoic acids are potent exogenous pyrogens, ie they are among the substances that cause a febrile reaction in man after a bacterial infection caused by gram- positive bacteria. They are recognized by the Toll-like receptor TLR -2, which is expressed on monocytes and dendritic cells, B and T lymphocytes and macrophages. Further they provide for the release of cytokines and are thus one of the main factors for the inflammatory response after such an infection.

Because of their antigenic property they are also interesting for the production of synthetic vaccines.

Swell

• Thomas Kohler: Studies on the biosynthesis and interaction of Zellwandteichonsäuren of Staphylococcus aureus., 2005.