Characterization of a cell-surface protein antigen of hydrophilic Streptococcus mutans strain GS-5.
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.
Ohta
H
H
Department of Dental Research, National Institute of Health, Tokyo, Japan.
Kato
H
H
Okahashi
N
N
Takahashi
I
I
Hamada
S
S
Koga
T
T
D000942:Antigens, Bacterial / Q000032:analysis*; D000954:Antigens, Surface / Q000032:analysis*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D007106:Immune Sera / Q000276:immunology; D013295:Streptococcus mutans / Q000145:classification / Q000276:immunology* / Q000502:physiology
D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001425:Bacterial Outer Membrane Proteins; D007106:Immune Sera