Structure of lipopolysaccharide

Figure 1 Structure of lipopolysaccharide (LPS) from gram-negative Salmonella species.

In the last decades, structural details of lipopolysaccharides derived from selected bacterial serotypes have been elucidated, and it became possible to ascribe distinct biological properties to distinct domains of the macromolecule. As a consequence, a number of organic chemists have undertaken the chemical synthesis of biologically relevant partial structures of lipopolysaccharide. 

Heine, H., Muller-Loennies, S., Brade, L., Lindner, B., Brade, H. Endotoxic activity and chemical structure of lipopolysaccharides from Chlamydia trachomatis serotypes E and L2 and Chlamydophila psittaci 6BC. Eur J Biochem 270 (2003) 440-450. 

Garidel, P., Rappolt, M., Schromm, A.B., Howe, J., Lohner, K., Andra, J., Koch, M.H., Brandenburg, K. Divalent cations affect chain mobility and aggregate structure of lipopolysaccharide from Salmonella minnesota reflected in a decrease of its biological activity, Biochim Biophys Acta 1715 (2005) 122-131. 

Knirel, Y.A., Kochetkov, N.K. The structure of lipopolysaccharides of Gram-negative bacteria. III. The strcucture of O antigens a review. Biochemistry (Moscow) 59 (1994) 1325-1383. 

Fig. 9.1 The structure of lipopolysaccharide, LPS. LPS consists of an O-specific antigen, a core oligosaccharide and the lipid A moiety. The core oligosaccharide, which varies from one bacterial species to another, is made up of outer and inner sugar regions. Lipid A virtually always includes two glucosamine residues modified by phosphates and a variable number of fatty acid chains (Frecer et al., 2000). The LPS structure was kindly contributed by Professor Helmut Brade (Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Medical and Biochemical Mikrobiology Parkallee 22, D-23845 Borstel, Germany)...

Russa, R., Urbanik-Sypniewska, T., Shashkov, A.S., Banaszek, A., Zamojski, A., Mayer, H. Partial structure of lipopolysaccharide isolated from Rhizobium leguminosarum bv. trifolii 24 and its GalA-negative Exo" mutant. System Appl Microbiol 19 (1996) 1-8. 

Seydel U, Brandenburg K (1992) Supramolecu-lar structure of lipopolysaccharides and lipid A. 

Figure 2.9 Generalized structures of lipopolysaccharide and lipid A. Abbreviations Abe, abequose Man, Mannose Rha, rhamnose Gal, galactose Glc, glucose Hep, heptose KDO, 3-deoxy-D-manno-octulosonic acid 0, phosphate EtN, ethanolamine M, myristate Mo, y3-hydroxymyristate. Reproduced with permission from Harwood and Russell (1984).

The lipopolysaccharides have been isolated from two wild-type strains of E. coli K12, two core-deficient mutants, and an SR recombinant with Salmonella typhimurium Methylation analysis of the oligosaccharides released on dephosphorylation of the lipopolysaccharides revealed differences in the extents of completion of the core structures. The non-reducing end of the complete core structure of lipopolysaccharides from the E. coli K12 wild-type strains is substituted with either 2-acetamido-2-deoxy-D-glucose or, possibly, 2-acetamido-2-deoxy-D-mannopyranosyluronic acid, whereas the complete K12 core in the SR recombinant is substituted with an S-specific oligosaccharide of S. typhimurium. These substituents are attached to 0-6 of the D-glucopyranosyl residue at the non-reducing end of the core oligosaccharide, as shown in (8). 

Hannecart E, Dekegel D, Dupuydt F. Macromolecular structure of lipopolysaccharides from gram-negative bacteria. Eur J Biochem 1973 38 6-13. 

Figure 6.19 Generalized structure of lipopolysaccharide from a gram-negative bacterium.

A structural study on lipid A and the O-specific polysaccharide of the lipopoly-saccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn s disease was conducted by Hashimoto and coworkers [39]. They separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. Next, they elucidated the strucmres of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by PLC, and its structure was determined by MS and NMR. 

Using PTLC six major fractions of lipids (phospholipids, free sterols, free fatty acids, triacylglycerols, methyl esters, and sterol esters) were separated from the skin lipids of chicken to smdy the penetration responses of Schistosoma cercaria and Austrobilharzia variglandis [79a]. To determine the structure of nontoxic lipids in lipopolysaccharides of Salmonella typhimurium, monophosphoryl lipids were separated from these lipids using PTLC. The separated fractions were used in FAB-MS to determine [3-hydroxymyristic acid, lauric acid, and 3-hydroxymyristic acids [79b]. 

The surface structure of gram-negative bacteria (these are not stained by Gram s method and must be stained red with carbol fuchsin) is more diversified. It consists of an outer membrane whose main building unit is a lipopolysaccharide together with phospholipids and proteins. The actual cell... 

Ferguson, A. D., Hofmann, E., Coulton, J. W., Diederichs, K. and Welte, W. (1998). Siderophore-mediated iron transport crystal structure of FhuA with bound lipopolysaccharide, Science, 282, 2215-2220. 

Plate 7 (Figure 8, Chapter 6, p. 306). Structure of the Escherichia coli FhuA protein serving as receptor for ferrichrome and the antibiotic albomycin. (a), side view (b), side aspect with partly removed barrel to allow the view on the cork domain (c), top view. A single lipopolysaccharide molecule is tightly associated with the transmembrane region of FhuA (reproduced by permission of W. Welte and A. Brosig)... 

O. Holst and H. Brade, in D. C. Morrison and J. L. Ryan (Eds.), Bacterial Endotoxic Lipopolysaccharides Chemical Structure of the Core Region of Lipopolysaccharides, p. 135. CRC Press, Boca Raton, FL, 1992. 

B. Lindner, U. Zahringer, E. Th. Rietschel, and U. Seydel, in A. Fox, S. L. Morgan, L. Larsson, and G. Odham (Eds.), Analytical Microbiology Methods Structural Elucidation of Lipopolysaccharides and Their Lipid A Component Application of Soft Ionization Mass Spectrometry, p. 149. Plenum, New York/London, 1990. 

Disadvantages The protein expressed is accumulated within the cell matrix (intracellular) the protein does not undergo posttranslational modifications (resulting in proteins that may be structurally different or less useful to humans) the presence of lipopolysaccharides (pyrogens—microbial substances that cause fever) is likely to contaminate the product and there is a need for more extensive chromatographic purification. 

Figure 3.37. Structure of a generalized lipopolysaccharide (LPS) molecule. LPS consitutes the major structural component of the outer membrane of Gram-negative bacteria. Although LPS of different Gramnegative organisms differ in their chemical structure, each consists of a complex polysacharide component, linked to a lipid component. Refer to text for specific details...

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