Teichuronic acid

Teichoic and teichuronic acids. The cell walls of gram-positive bacteria are composed of a thick peptidoglycan layer which also contains proteins and additional polymers known as teichoic acids and teichuronic acids. In some species these account for 50% of the dry weight of the cells.598 599 Teichoic acids are high polymers of the following general types ... 

Teichoic acids are often covalently attached to glycolipids which are part of the plasma membrane. For example, the glycerolteichoic acid of Streptococcus faecium contains about 28 monomer units of glycerol phosphate, approximately 60% of which carry residues of kojibiose (Glual —> 2Glu) as a phosphatidylkojibiosyl diacylglycerol membrane anchor.600 Teichuronic acids contain uronic acids ... 

Epimerization at C-2 of UDP-GlcNAc, leading to the UDP derivative of 2-acetamido-2-deoxy-D-mannose, was also observed115 118 the monosaccharide was identified as a constituent of several capsular polysaccharides from Streptococcus pneumonia119-122 and Neisseria meningitidis group A (Ref. 123), the teichuronic acid of Bacillus cereus,124 and the O-specific... 

Carbohydrate chains of teichuronic acids and neutral polysaccharides linked to the carbohydrate chains of peptidoglycans are fragments of macromolecules of Gram-positive cell-wall. Only two examples of the biosynthesis of these polymers have been studied in detail. Evidence for both block and monomeric mechanisms of the chain assembly was obtained. 

Modifications of the amino-acid composition of pseudomurein could be induced by addition of glycine, threonine, ornithine, or aspartic acid in elevated concentrations to the culture medium [21]. The isolated sacculi from several species also contain varying amounts of monosaccharides (Table 2). They could be extracted with hot formamide, indicating that they belong to polysaccharides associated with but not covalently bound to pseudomurein. Teichoic acid or teichuronic acid-like polymers are, however, not present in gram-positive methanogens. 

Fig. 6. Comparison of building blocks of (A) methanochondroitin of Methanosarcina sp. (B) teichuronic acid of Bacillus licheniformis (C) chondroitin sulfate of animal connective tissue.

Figure 5.5.1. A scatter plot of the intensity of ion with m/z =125 as a function of ion with m/z = 43 for (a) chitin, (b) chondroitin sulfate, (c) chitosan, (d) capsular polysaccharide from Neiseria meningitidis [47], (e) teichuronic acid from Bacillus subtilis [47], (f) carrageenan, (g) alginic acid, (h) amylose, (i) agarose.

Figure 7.9.1. Py-MS spectrum obtained using 14 eV excitation energy [3] and 51(f C pyrolysis for teichuronic acid from Bacillus subtllis.

Bacterial polysaccharides can also serve as markers to identify specific bacterial species or genera. Typical microbial polysaccharides include peptidoglycans, lipopolysaccharides, and teichoic/teichuronic acids. Some markers such as muramic acid, D-alanine, and p-hydroxy myristic acid are present in the polysaccharides from eubacteria but are uncommon in higher life forms such as plants and animals. Pyrolysis results on bacterial polysaccharides were discussed in Sections 7.9 and 7.10. Specific pyrolysis products such as propionamide or peaks characteristic for KDO have been used for Py-MS or Py-GC/MS characterization of microorganisms. 

Gram-positive bacteria also have additional anionic polymers (secondary cell-wall polymers, SCWPs), which are covalently attached to the muramic acid residues of the peptidoglyean and attach cell-surface proteins. They can be of the teichoic acid type, linear copolymers of a sugar alcohol and phosphoric acid, or the teichuronic acid type, in which the anionic component is uronic acids.The commonest teichoic acids are based on 1,3-linked glycerol or 1,5-linked ribitol. 

Novobiocin has been found to inhibit the synthesis of teichuronic acid by cellular extracts of B. licheniformis [41], but as this occurs only at concentrations of antibiotic much greater than the minimal concentration needed to inhibit growth, it is difficult to propose that this is its primary effect. 

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