Molecular interactions of alanine-rich and proline-rich regions of cell surface protein antigen c in Streptococcus mutans

M. Matsumoto-Nakano, M. Tsuji, A. Amano, T. Ooshima

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7 Citations (Scopus)


Introduction: Streptococcus mutans has been implicated as a primary causative agent of dental caries in humans, and its cell surface protein antigen c (PAc) is known to be associated with sucrose-independent adhesion to tooth surfaces. PAc is composed of several domains, including an N-terminal signal sequence, an alanine-rich repeat region (A-region), a proline-rich repeat region (P-region), and an anchor region. Methods: To investigate the functions of each domain, an A-region-deficient mutant strain of S. mutans was constructed, and recombinant PAc and A- and P-region proteins were also constructed. The interactions of each domain with the recombinant proteins were analyzed using surface plasmon resonance spectroscopy with a biomolecular interaction analyzing system. Results: The A-region-deficient mutant strain showed the lowest levels of adherence to saliva-coated hydroxyapatite. Furthermore, findings in an immunoblot assay indicated that the A-region protein reacted strongly with proline-rich proteins in saliva, while the recombinant P-region protein interacted more quickly with PAc than the recombinant A-region protein. Conclusion: These results suggest that the A-region has a strong relationship with adhesion to tooth surfaces, while the P-region has a high affinity for PAc.

Original languageEnglish
Pages (from-to)265-270
Number of pages6
JournalOral microbiology and immunology
Issue number4
Publication statusPublished - Aug 1 2008
Externally publishedYes



  • Functional domain
  • Protein antigen c
  • Streptococcus mutans

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Dentistry(all)
  • Microbiology (medical)

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