Streptococcus mutans strains harboring collagen-binding adhesin

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Adhesins

Background:

• Streptococcus mutans is a key pathogen in dental caries.
• Bacterial adhesins play crucial roles in host-pathogen interactions.
• The function of many S. mutans surface proteins remains uncharacterized.

Purpose of the Study:

• To identify and characterize a novel protein involved in Streptococcus mutans agglutination.
• To determine the molecular function and binding properties of the identified protein.
• To investigate the prevalence and significance of this protein in S. mutans strains.

Main Methods:

• Random mutagenesis of Streptococcus mutans strain Z1.
• Gene identification and sequencing (cnm gene).
• Recombinant protein expression in E. coli and binding assays with collagen, laminin, and fibronectin.

Main Results:

• A 120-kDa protein, encoded by the cnm gene, was identified and linked to cold-agglutination.
• The deduced Cnm protein sequence shows similarity to known collagen-binding adhesins.
• Recombinant Cnm protein demonstrated binding to collagen and laminin, but not fibronectin.
• A cnm mutant exhibited reduced binding to collagen and laminin.

Conclusions:

• The cnm gene encodes a novel, strain-specific collagen-binding adhesin in Streptococcus mutans.
• This adhesin contributes to bacterial agglutination and interactions with host matrix proteins.
• The findings expand our understanding of virulence factors in S. mutans.