Structural and antigenic types of cell wall polysaccharides from viridans group streptococci with receptors for oral actinomyces and streptococcal lectins.
Lectin-mediated interactions between oral viridans group streptococci and actinomyces may play an important role in microbial colonization of the tooth surface. The presence of two host-like motifs, either GalNAc beta1-->3Gal (Gn) or Gal beta1-->3GalNAc (G), in the cell wall polysaccharides of five streptococcal strains accounts for the lactose-sensitive coaggregations of these bacteria with Actinomyces naeslundii. Three streptococcal strains which have Gn-containing polysaccharides also participate in GalNAc-sensitive coaggregations with strains of Streptococcus gordonii and S. sanguis. Each Gn- or G-containing polysaccharide is composed of a distinct phosphodiester-linked hexa- or heptasaccharide repeating unit. The occurrence of these polysaccharides on 19 additional viridans group streptococcal strains that participate in lactose-sensitive coaggregations with actinomyces was examined. Negatively charged polysaccharides that reacted with Bauhinia purpurea agglutinin, a Gal and GalNAc binding plant lectin, were isolated from 17 strains by anion exchange column chromatography of mutanolysin-cell wall digests. Results from nuclear magnetic resonance and immunodiffusion identified each of 16 polysaccharides as a known Gn- or G-containing structural type and one polysaccharide as a new but closely related Gn-containing type. Unlike the reactions of lectins, the cross-reactions of most rabbit antisera with these polysaccharides were correlated with structural features other than the host-like motifs. Gn-containing polysaccharides occurred primarily on the strains of S. sanguis and S. oralis while G-containing polysaccharides were more common among the strains of S. gordonii and S. mitis examined. The findings strongly support the hypothesis that lectin-mediated recognition of these streptococci by other oral bacteria depends on a family of antigenically diverse Gn- and G-containing cell wall polysaccharides, the occurrence of which may differ between streptococcal species.
Cisar
J O
JO
Oral Infection and Immunity Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA. jcisar@yoda.nidr.nih.gov
Sandberg
A L
AL
Reddy
G P
GP
Abeygunawardana
C
C
Bush
C A
CA
D000190:Actinomyces / Q000378:metabolism; D000818:Animals; D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000378:metabolism*; D037102:Lectins; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism*; D013289:Streptococcaceae / Q000378:metabolism*
D037102:Lectins; D011135:Polysaccharides, Bacterial; D011956:Receptors, Cell Surface