K-antigens

Resistance to phagocytosis is sometimes associated with specific components of the cell wall and/or with the presence of capsules surrounding the cell wall. Classic examples of these are the M-proteins of the streptococci and the polysaccharide capsules of pneumococci. The acidic polysaccharide K-antigens of Escherichia coli and Sal typhi behave similarly, in that (i) they can mediate attachment to the intestinal epithelial cells, and (ii) they render phagocytosis more difficult. Generally, possession of an extracellular capsule will reduce the likelihood of phagocytosis. 

Shi S-R, Key M, Kalra K. Antigen retrieval in formalin-fixed, paraffin-embedded tissues an enhancement method for immunohistochemical staining based on microwave oven heating of tissue sections. J. Histochem. Cytochem. 1991 39 741-748. 

The first report of the occurrence of KDO in a structure other than LPS was that of Taylor47 on the capsular polysaccharide (K-antigen) of a clinical isolate, Escherichia coli LP1092. Almost simultaneously, Bhattachaijee and coworkers83 described an exopolysaccharide from Neisseria meningitidis serogroup 29e. This material contains KDO... 

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... 

As an approach to the synthesis of trisaccharide 46, which corresponds to a repeating unit of the K antigen from E. coli LP 1092, the intermediate J , has also been glycosidated with the disaccharide halide 4 4 under the conditions given by Hanessian (35). 

K ANTIGENS ARE ACIDIC POLYSACCHARIDES MOLECULAR WEIGHTS BELOW 50 000... 

Figure 7. Characteristic proton signals of KDO and KDO-containing K antigens.

Thus, lipopolysaccharides are potent pyrogens in man and rabbits. Furthermore, they are mitogens for B-lymphocytes (mouse) and they induce lethal toxicity in various experimental animals (.7). The lipoprotein (IS. coli) is also a B-cell mitogen it is, however, devoid of pyrogenicity and lethal toxicity (6). K-antigens and the enterobacterial common antigen lack all of these latter activities. 

One clear example of the importance of capsular polysaccharides is in the symbiotic relationship between nitrogen-fixing rhizobial bacteria and leguminous plants, where MS has played a central role in helping elucidate structures. Here we aim to highlight, using the specific example of bacterial K-antigen studies, the central role of modern mass-spectrometric techniques in polysaccharide analysis. 

B. L. Reuhs, R. W. Carlson, and J. S. Kim, Rhizobium fredii and Rhizobium meliloti produce 3-deoxy-D-marmo-2-octulosonic acid-containing polysaccharides that are structurally analogous to group II K antigens (capsular polysaccharides) found in Escherichia coli, J. Bacteriol., 175 (1993) 3570-3580. 

B. L. Reuhs, D. P. Geller, J. S. Kim, J. E. Fox, V. S. Kumar Kolli, and S. G. Pueppke, Sinorhizobium fredii and Sinorhizobium meliloti produce structurally conserved lipopolysaccha-rides and strain-specific K antigens, Appl. Environ. Microbiol., 64 (1998) 4930 1938. 

Kannenberg, E.L., Reuhs, B.L., Forsberg, L.S., Carlson, R.W. Lipopolysaccharides, K-antigens Their structures, biosynthesis, and function. In Spaink, H.P., Kondorosi, A., Hooykaas, P.J.J (eds.), The Rhizobiaceae Molecular Biology of Model Plant-Associated Bacteria. Kluwer Academic Publishers, Dordrecht/Boston/London (1998), pp. 119-154. 

Reuhs, B.L., Stephens, S.B., Geller, D.P., Kim, J.S., Glenn, J., Przytycki, J., Ojanen-Reuhs, T. Epitope identification for a panel of unli-Sinoritizobium meliloti monoclonal antibodies and application to the analysis of K antigens and lipopolysaccharides from bacteroids. Appl Environ Microbiol 65 (1999) 5186-5191. 

It is interesting that polysaccharides obtained from O inagglutinable, capsular strains (having K antigens) were reported to contain uronic acid neutral sugars were also present, however, and 0 antigen specificity was also detected in the products. 

In the case of Aerobaoter aerogenes, much more information is available. A large number of serological types due to K antigen polysaccharides have been described. Fifty-seven of these were examined by their infrared... 

Constituent of the cell wall polysaccharide of a strain of Actinomyces bovis and the K-antigen... 

Stroup R, Sheibani K. Antigenic phenotypes of hairy cell leukemia and monocytoid B-cell lymphoma an immunohistochemical evaluation of 66 cases. Hum Pathol. 1992 23(2) 172-177. 

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