Comparison of Streptococcus mutans and Streptococcus sanguis receptors for human salivary agglutinin.
Oral streptococci vary in their susceptibility to salivary agglutinin-mediated aggregation. To understand the molecular basis of this specificity, the structure and function of receptors for agglutinin from Streptococcus mutans KPSK2 (MSL-1) and Streptococcus sanguis M5 (SSP-5) were compared. Immunological screening of an S. mutans KPSK2 genomic DNA library yielded two identical clones expressing a streptococcal protein that co-migrated with a 220 kDa peptide in SDS extracts from this organism. This protein inhibited agglutinin-mediated aggregation of S. mutans KPSK2 in a dose-dependent manner. The MSL-1 gene is homologous to the S. mutans SpaP and pac genes although single base substitutions alter several amino acids. MSL-1 is also similar to the agglutinin receptor (SSP-5) cloned from S. sanguis M5. All three proteins, MSL-1, P1, and SSP-5 share at least one epitope since monoclonal and polyclonal anti-SSP-5 antibodies react with both MSL-1 and P1. However, other monoclonal antibodies are specific for SSP-5 and appear to react with a peptide domain exhibiting little homology to MSL-1 or P1. Sugar inhibition studies showed that agglutinin-mediated aggregation of S. mutans KPSK2 was most potently inhibited by fucose and lactose. Sialic acid, a potent inhibitor of S. sanguis aggregation, had no effect on the interaction of agglutinin with S. mutans KPSK2. These results suggest that while the MSL-1 and SSP-5 proteins are genetically and immunologically related, their specificity for binding sites on agglutinin differs.
Demuth
D R
DR
Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104.
Lammey
M S
MS
Huck
M
M
Lally
E T
ET
Malamud
D
D
D018829:Adhesins, Bacterial; D000373:Agglutinins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D003001:Cloning, Molecular; D000939:Epitopes; D005798:Genes, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D011975:Receptors, Mitogen / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D012463:Saliva / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013295:Streptococcus mutans / Q000235:genetics* / Q000378:metabolism; D013298:Streptococcus sanguis / Q000235:genetics* / Q000378:metabolism
D018829:Adhesins, Bacterial; D000373:Agglutinins; D000911:Antibodies, Monoclonal; D000939:Epitopes; D011975:Receptors, Mitogen; C068465:salivary agglutinin receptor, Streptocococcus