Pathogenicity, polysaccharide structure

Each polysaccharide structure is synthesized by a distinct set of enzymes, and the biosyntheses of the individual structures will not be discussed here. The biosynthetic gene clusters for many different capsular and extracellular polysaccharides are known, and many of the enzymes involved have been characterized. For a general review of the genetics and biochemistry of CPS production, the reader is referred to a review by Roberts [321]. There are also many excellent reviews discussing capsule formation in individual bacteria, including H. influenzae [322], S. Aureus [323], E. coli [312], and pathogenic streptococci [324,325]. 

These protruding structures may form catalytic sites or binding sites for small molecules. Remarkably, some polysaccharide modification enzymes of pathogenic bacteria are similar to enzymes of their host cells. For example, during cell development, pectin, a principal component in the primary cell wall of plants, is modified by its own pectin methylesterases that have /1-solenoid structures (Johansson et al, 2002) and in this respect, resemble pectin lyases secreted by bacteria to break down these structures (Lietzke et al., 1996). 

H. J. Jennings Structure, conformation and immunology of the polysaccharide capsules of human pathogenic bacteria... 

Glucuronic acid is also constituent of pathogenic bacteria. The simplest structure for a pneumococcal capsular polysaccharide has the repeating unit [- 4)-/3-d-G1c-(1 3)-/3-D-GlcpA-(l ]ra.120... 

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