Bacterial Adhesion Lectins

Microbial pathogens utilize different types of lectins for targeting the glycans on the surface of host cells. Many bacteria are covered with pili or fimbriae that contain a very special class of lectins known as adhesins because they play a role in attachment to epithelial cells. These lectins are monomeric and comprise only one binding site. Because the adhesins are repeated on the pilus, a larger number of adhesins on the bacterial surface create multivalent interaction with the host glycans. 

FIGURE 16.9 Selected mannosylated glycocluster based on (a) a carbohydrate and (b) an L-lysine core used as a potential antagonist against Escherichia coli FimH. 

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More recently, increasing research attention has focused upon the use of mucoadhe-sive delivery systems in which the biopharmaceutical is formulated with/encapsulated in molecules that interact with the intestinal mucosa membranes. The strategy is obviously to retain the drug at the absorbing surface for a prolonged period. Non-specific (charge-based) interactions can be achieved by the use of polyacrylic acid, whereas more biospecihc interactions are achieved by using selected lectins or bacterial adhesion proteins. Despite intensive efforts, however, the successful delivery of biopharmaceuticals via the oral route remains some way off. 

TSome microbial pathogens have lectins that mediate bacterial adhesion to host cells or toxin entry into cells. The bacterium believed responsible for most gastric ulcers, Helicobacter pylori, adheres to the inner surface of the stomach by interactions between bacterial membrane lectins and specific oligosaccharides of membrane glycoproteins of the gastric epithelial cells... 

Examination of specific carbohydrate-protein interactions can be accomplished with C-glycosides (Scheme 1). A series of C-glucosides and C-mannosides, such as 1, were employed to study the binding differences between mannose and glucose specific lectins (9). C-Mannoside derivatives (3-5) were synthesized from C-allyl derivative 2 and used to block cell-surface lectins thereby inhibiting bacterial adhesion (JO). The primary amine of 4 was functionalized with biotin to target proteins to the bacterial cell surface. 

Keywords Assembly, Bacterial adhesion, Chaperone/Usher pathway, Fimbriae/ Pili, Lectin... 

Specific targeting of drngs to the absorption site achieved by anchoring plant lectins, bacterial adhesions, and antibodies, etc., on the surface of the microspheres... 

From the literature, little is known about specific interactions in bacterial adhesion to polymers. In the adhesion of S. sanquis to saliva-coated hydroxyl apatite (HA), the existence of two specific receptor sites on HA could be demonstrated to which sialic acid lectins can bind. Vaudaux, et al., found in adhesion experiments of S. aureus to fibronectin-coated PMMA coverslips, that presumably a specific site in the amino-terminal region of fibronectin is involved in the adhesion process, and that collagen may play a role as an adhesion cofactor. 

By virtue of promising preliminary biological results indicating that tri- and tetravalent glycoclusters constitute potent inhibitors of bacterial binding, which fitted particularly well into the CRD of bacterial lectins (especially for mannose-specific adhesion) straightforward syntheses of low-valency glycoclusters were initiated. 

The adhesion of bacterial and viral pathogens to their animal-cell targets occurs through binding of lectins in the pathogens to... 

Adhesion to the digestive tract wall to prevent colonisation by pathogenic microorganisms Detrimental bacteria, such as E. coli, need to become attached to the gut waU to exert their harmful effects. Attachment is achieved by means of hairlike structures, called fimbriae, on the bacterial surface. The fimbriae are made up of proteins, called lectins, which recognise and selectively combine with specific oligosaccharide receptor sites on the gut wall. Lactobacilli successfully compete for these attachment sites, as shown in Fig. 24.1. 

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