Structure, function and immunogenicity of streptococcal antigen I/II polypeptides

Mol Microbiol. 1997 Jan;23(2):183-90. doi: 10.1046/j.1365-2958.1997.2021577.x.


The antigen I/II family of cell-surface-anchored polypeptides in oral streptococci are structurally complex multi-functional adhesins, with multiple ligand-binding sites. Discrete regions within these polypeptides bind human salivary glycoproteins, other microbial cells, and calcium. Sequences within the N-terminal region bind preferentially fluid-phase glycoproteins, while the C-terminal half of the polypeptide contains species-specific adhesion-mediating sequences that bind surface-immobilized glycoproteins. These features may assist streptococcal adhesion to oral surface receptors despite the presence of excess fluid-phase receptors. Immunological studies reveal an array of T-cell and B-cell epitopes presented by antigen I/II polypeptides and suggest the occurrence of natural suppression of human antibodies to the adhesion-mediating sequences. The functional and immunological properties of antigen I/II proteins may account to a major extent for the success of oral streptococci colonizing and surviving within the human host.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Antigens, Bacterial / genetics*
  • Antigens, Bacterial / immunology*
  • Bacterial Outer Membrane Proteins / genetics*
  • Bacterial Outer Membrane Proteins / immunology*
  • Bacterial Proteins*
  • Epitopes, B-Lymphocyte / immunology
  • Epitopes, T-Lymphocyte / immunology
  • Humans
  • Membrane Glycoproteins / genetics*
  • Membrane Glycoproteins / immunology*
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Streptococcus / genetics*
  • Streptococcus / immunology*
  • Streptococcus / physiology


  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Epitopes, B-Lymphocyte
  • Epitopes, T-Lymphocyte
  • Membrane Glycoproteins
  • S-layer proteins