Characterization of a cell-surface protein antigen of hydrophilic Streptococcus mutans strain GS-5

J Gen Microbiol. 1989 Apr;135(4):981-8. doi: 10.1099/00221287-135-4-981.


Fourteen strains of Streptococcus mutans serotype c were examined for their cell-surface protein antigens in terms of hydrophobicity, Mr and immunochemical specificities. Thirteen strains were hydrophobic, while strain GS-5 was markedly hydrophilic as compared to the other strains tested. Cell-surface protein antigens were then analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western immunoblotting. A protein antigen of Mr 190,000 (PAc) was found in cell extracts and culture supernatants of all the hydrophobic strains. Neither culture supernatant nor cell extract of strain GS-5 contained PAc. Strain GS-5, however, produced extracellularly a large amount of a protein of Mr 155,000 (PAGS-5) which reacted with rabbit anti-PAc serum. Immunodiffusion analysis showed that PAGS-5 lacked a part of the antigenic moieties in the PAc molecule. SDS-PAGE and radioimmunoassay showed a small amount of PAGS-5 on the cell surface of strain GS-5. These findings suggest that PAGS-5 may correspond to PAc which lacks a region participating in binding of PAc to the streptococcal cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Bacterial / analysis*
  • Antigens, Surface / analysis*
  • Bacterial Outer Membrane Proteins / immunology
  • Blotting, Western
  • Electrophoresis, Polyacrylamide Gel
  • Immune Sera / immunology
  • Streptococcus mutans / classification
  • Streptococcus mutans / immunology*
  • Streptococcus mutans / physiology


  • Antigens, Bacterial
  • Antigens, Surface
  • Bacterial Outer Membrane Proteins
  • Immune Sera