Mannose-specific adhesion

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. 

FimH is the mannose-specific adhesive subunit of type 1 fimbriae and located at the tip of this organelle [24], However, its presence in the fimbrial shaft has also been described which only becomes active upon fragmentation of the fimbrial shaft which in turn leads to the exposure of the binding site [25], In addition to UPEC strains, type 1 fimbriae are expressed by a large number of other E. coli isolates,... 

K. Drickamer, and A.-C. Roche, Oligolysine-based oligosaccharide clusters selective recognition and endocytosis by the mannose receptor and dendritic cell-specific intercellular adhesion molecule 3 (ICAM-3)-grabbing nonintegrin, /. Biol. Chem., 278 (2003) 23922-23929. 

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. 

Among the fungal and protozoal lectins only a few have been studied in detail. One of these is the galactose-specific lectin of the protozoa Entamoeba histolytica. It mediates adhesion of the parasite to human colonic mucin glycoproteins and has a central role in the contact-dependent cytolysis or histolysis for which the parasite is named. A sialic-acid-speeific lectin has been isolated from merozoites of the human malarial parasite, Plasmodium falciparum. An unusual lectin is that of the protozoan Giardia lamblia, specific for mannose-6-phosphate, which is activated by trypsinization. 

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