Klebsiella Polysaccharides structures

Serological testing has revealed seventy-seven different types of Klebsiella and structures for the capsular polysaccharide have been proposed for 55. Some typical Klebsiella polysaccharide structures are listed in Table 2. 

K38 is another Klebsiella polysaccharide that incorporates a 1, 6 linkage in its backbone and in addition has the distinctive feature of incorporating a 3-deoxy-L-glycero-pentulosonic acid residue in its asymmetric unit (5) (Figure 12). Figure 13 is a typical X-ray diffraction pattern obtained from this material and shows that the molecule forms an extended 2-fold helical structure. 

The final Klebsiella polysaccharide that will be mentioned specifically is KZS, whose chemical structure was determined by Niemann et al (24) (Figure 30). This polysaccharide is of particular interesT because its backbone consists of a similar alternating 1, 3 diequatorial, 1, 4 diequatorial glycosidic linkage geometry to that found in the connective tissue polysaccharides, hyaluronic acid, chondroitin sulphate and dermatan sulphate (25). All these three polysaccharides have exhibited 3-fold helical conformations with axially projected chemical repeats in the range 0.95 - 0.97 nm which is comparable to 0.97 nm found in K25 which also forms a 3-fold helix (14). Further, left-handed helices were found to be more favourable in K25 as has previously been observed in the connective tissue polysaccharides. The similarities between these various different structures is apparent in Figure 31 which shows projections down the axis of K25 and several of the connective tissue polysaccharides. 

There are many Klebsiella polysaccharides still to be investigated. In several instances very good X-ray diffraction patterns have been obtained and further investigation awaits the full elucidation of the chemical structure. On the other hand, several have been disappointing in showing no inclination to crystallise and/or orientate. We can see no inherent reason why they should not, and can only hope that a fresh batch of material may be more productive. 

Elloway HF, Isaac DH, Atkins EDT (1980) Review of the structures of Klebsiella polysaccharides by X-ray diffraction. Chap. 27. In French AD, Gardner KH (eds) Fiber diffraction methods. Am Chem Soc Symp Ser 141 429-458... 

To overcome the limitations of chemical degradations such as low yields of oligosaccharides, low specificity and complicating side reactions, the use of specific enzymes offers great potential in structural polysaccharide chemistry. Probably the most successful application of enzymes has been the use of bacteriophage endoglycanases (Rieger-Hug and Stirm, 1981) for the structural analysis of Klebsiella polysaccharides (Dutton et al., 1981 Dutton and Merrifield, 1982). 

Structural studies on the oligosaccharide derivatives obtained by partial, acid hydrolysis of fully methylated polysaccharides often furnish valuable information on the positions at which the oligosaccharides were linked in the original polysaccharide. When the folly methylated Klebsiella O group 9 lipopolysaccharide,27 which contains D-galactopyranose and D-galactoforanose residues, was subjected to mild, acid hydrolysis, and the product reduced with lithium aluminum deuteride and remethylated with trideuteriomethyl iodide, a good yield of the disaccharide derivative 10 was obtained. 

Further examples of modified Smith degradation, in which the polyalcohol is methylated prior to hydrolysis under mild conditions, uronic acid degradation, and /3-elimination preceded by oxidation have been reported in connection with structural studies on the Klebsiella type 28 (Ref. 182), 57 (Ref. 183), 59 (Ref. 142), and 81 (Ref. 184) capsular polysaccharides. 

The primary structure of the Klebsiella K8 capsular polysaccharide was established by Sutherland (3). It is a poly(tetrasaccharide) with three sugar residues in the backbone and a monosaccharide side-chain (II). 

The molecular structure of polysaccharides from Klebsiella serotype K8 has been examined by X-ray diffraction and computer-aided molecular modeling. The most favorable molecular model was not the one which had the maximum number of intra-molecular hydrogen bonds. This result suggests that in the analysis one should not a priori choose the molecular model which has the largest number of intra-molecular hydrogen bonds. 

Figure 1. Variety of structural patterns found among Klebsiella bacterial polysaccharides...

It is interesting to compare the structure of Klebsiella K5 with that of Klebsiella K63 which, as can be seen from figure 1, is the only other linear trisaccharide so far found in the Klebsiella group. The chemical structure of K63 as determined by J-P. Joseleau, Grenoble (personal communcation) is shown in Figure 5 and Figure 6 shows an X-ray diffraction pattern obtained (in collaboration with Dr. H. Chanzy, Grenoble) from this material. This pattern showed that, like K5 polysaccharide,... 

Y. A. Knirel, N. A. Kocharova, A. S. Shashkov, N. K. Kochetkov, V. A. Mamontova, and T. F. Solov eva, Structure of the capsular polysaccharide of Klebsiella ozaenae serotype K4 containing 3-deoxy-D-g(ycero-D-gra/acta-nonulosonic acid, Carbohydr. Res., 188 (1989) 145-155. 

B. Lindberg and K. Samuelson, The Klebsiella type 38 capsular polysaccharide identification of 3-deoxy-L-g-(ycCTO-pentulosonic acid and structural studies, Carbohydr. Res., 30 (1973) 63-70. 

Rather uncommon are the two pyruvic acetal structures which have been identified in Klebsiella K12 capsular polysaccharides and in the teichoic acid of bacterium NCTC 9742 [10]. In the former case, a 4,5-0-(l-carboxyethylidene)- -D-galactofuranosyl residue was found at the side chain terminus of the hexa-saccharide repeating unit. In the latter case, the teichoic acid contains intra-catenally bound 2,3-0-(l-carboxyethylidene)-D-mannitol phosphate. No data about the configuration of these pyruvic acetals are available. 

J. J. Zhang, Y. Zhu, and F. Kong, Synthesis of an L-rhamnose tetrasaccharide, the common and major structure of the repeating unit of the O-antigenic polysaccharide of a strain of Klebsiella pneumoniae and Pseudomonas hold, Carbohydr. Res., 336 (2001) 229-235. 

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