Bacteria polysaccharide biosynthesis

Polyisoprenol compounds exist in both bacteria and eukaryotic cells. They participate in the synthesis of bacterial polysaccharides and in the biosynthesis of N-... 

An attractive hypothesis is the independent evolution in bacteria of their diffusible individualites and the currently recognized secondary metabolic pathways, in parallel with their surface components and their biosynthesis. An indicator for this would be the use of the same gene pool. The theory would include all substances that play a role in the build-up of glycan and other modified surface layers, lipids, murein, (glyco-) proteins (e.g., S-layers), polysaccharides, teichoic... 

Branched-chain monosaccharides have now been detected as components of bacterial polysaccharides. The known examples include yersiniose [3,6-dideoxy-4-C-(hydroxyethyl)-D-xy/o-hexose228] from Y. pseudotuberculosis, a 3-C-(hydroxymethyl)pentofuranose from Coxiella bumetti,229 and 6-deoxy-3-C-methylhexoses from the same organism and from Nitrobacter hamburgiensis.229 Several branched-chain monosaccharides were identified as components of antibiotics, and the pathways of their biosynthesis in bacteria were studied. These investigations were discussed in detail by Grisebach in this Series.230 The usual precursors for the formation of the monosaccharides of this group are the nucleoside 6-deoxyhexosyl-4-ulose diphosphates 7a and 7b. 

Because of its roles in the synthesis of glycogen, in isomerization of hexose phosphates, and as a precursor for numerous biosynthetic intermediates, UDP-glucose is regarded as a central hexose derivative in mammalian metabolism. In bacteria and plants, both ADP-glucose (production of storage polysaccharide) and UDP-glucose (sugar interconversions and biosynthesis) play important roles as precursors. 

The 3-deoxy-D-ma/ino-2-octulosonic acid 8-phosphate synthase (KDO synthase or KdoS EC 4.1.2.16) is an enzyme involved in the biosynthesis of the eight-carbon sugar KDO [63], a constituent of the capsular polysaccharides (K-antigens) and outer membrane lipopolysaccharides (LPS, endotoxin) of Gram-negative bacteria [156], as well as of the cell wall of algae and a variety of plants [157], In vivo, the enzyme catalyzes the irreversible addition of 26 to D-arabinose 5-phosphate (Ara5P, 32) to form KDO 8-phosphate 33 [158]. The... 

In 1923 antibodies specific for a polysaccharide in the pneumococcal cell wall were detected in the serum from rabbits immunized with non-viable pneumococcal cells by Heidelberger and Avery [1], Cell wall polysaccharides from other bacteria as reported by Lancefield [2], McCarty [3], Krause [4], Pazur [5], and Karakawa [6] activated the plasma cells in the serum of animals to initiate the biosynthesis of antibodies which were specific for the carbohydrates. Such antibodies are appropriately classified as anticarbohydrate antibodies. The antibodies which are synthesized on immunization are polyclonal antibodies and consist of various numbers of isoforms. The antibodies which are synthesized by fusion of immune spleen cells and myeloma cells are monoclonal antibodies. 

The peptidoglycan layer confers mechanical stability to the cell wall of the bacteria. An important intermediate of the peptidoglycan biosynthesis is the GlcNAc- MurNAc-L-Ala-D-y-Gln-L-Lys-D-Ala-D-Ala peptide (muramyl-pentapeptide), which is in its lipid-carrrier bound form transglycosylated to a linear polysaccharide. The linear polysaccharide is then cross-linked to peptidoglycan by transpeptidation reactions. Perkins observed that vancomycin binds to the Lys-D-Ala-D-Ala peptide motif of bacterial cell wall intermediates. This observation was later investigated on a mole-cular level by NMR and by x-ray crystallographic studies. ... 

In the previous edition of this book, Todd Lowary exhaustively reviewed what was known to date about the structure, function and bios)uithesis of the mycobacterial cell wall polysaccharides, as well as chemical syntheses of substrates and inhibitors for the biosynthetic enzymes [21]. Cell wall biosynthesis remains better studied in mycobacteria than in the other mycolata because of the obvious medical significance of these bacteria. The purpose of this section is therefore to highlight more recent developments in the study of the mycobacterial cell wall, and to describe some of the variation in cell wall stmcture seen among different genera within the mycolata. 

Structures of mammalian glycosaminoglycans the anti-thrombin-binding pentasaccharide in heparin/HS, a CS polysaccharide, and a mammalian HA. [Reproduced with permission from K. Lidholt, Biosynthesis of glycosaminoglycans in mammalian cells and in bacteria. Biochem. Soc. Trans. 25 866 (1997).]... 

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