LECTIN RECOGNITION OF HOST-LIKE SACCHARIDE MOTIFS IN STREPTOCOCCAL CELL-WALL POLYSACCHARIDES

Viridans streptococci that participate in the microbial colonization o f teeth have cell wall polysaccharides composed of linear phosphodiest er-linked hexa- or heptasaccharide repeating units, each containing a host-like disaccharide motif, either Gal beta 1-->3GalNAc or GalNAc be ta 1-->3Gal. Whereas strains with GalNAc beta 1-->3Gal-containing poly saccharides co-aggregated with streptococci that possess GalNAc-sensit ive lectins, strains with either host-like moth co-aggregated with Act inomyces spp, The latter interactions reflected the specificity of Act inomyces spp, lectins for common features of Gal beta 1-->3GalNAc and GalNAc beta 1--> 3Gal, Thus, alpha-linked glycosides of both disacchar ides were much more potent inhibitors of co-aggregation than Gal or Ga lNAc Six non-bacterial lectins also reacted with the streptococcal pol ysaccharides, In general, precipitation of each lectin with each polys accharide involved binding of Gal or GalNAc within the host-like moths , but not saccharides outside these regions, The lectins of Ricinus co mmunis, Abrus precatorius, Codium fragile and Agaricus bisporus were m ost reactive with the Gal beta 1-->3GalNAc-containing polysaccharides, the Wisteria floribunda lectin with the GalNAc beta 1-->3Gal-containi ng polysaccharides and the Bauhinia purpurea lectin with polysaccharid es containing either disaccharide, Thus, lectin recognition of the str eptococcal cell wall polysaccharides involved either the common or spe cific sides of the Gal beta 1-->3GalNAc and GalNAc beta 1-->3Gal moths present within these molecules.