Functional amyloid formation by Streptococcus mutans

Area of Science:

• Microbiology
• Oral Health
• Biochemistry

Background:

• Dental caries is a prevalent infectious disease caused by acidogenic bacteria like Streptococcus mutans.
• These bacteria form resilient biofilms, producing acids from sugars and tolerating acidic environments.
• Microbial functional amyloids are increasingly recognized as crucial for biofilm development.

Purpose of the Study:

• To investigate whether Streptococcus mutans produces functional amyloids.
• To determine the role of amyloid formation in Streptococcus mutans biofilm development.
• To identify specific amyloid-forming proteins in Streptococcus mutans.

Main Methods:

• Amyloid properties of the S. mutans P1 adhesin were assessed using Congo red and Thioflavin T dyes.
• Amyloid fibers were visualized via transmission electron microscopy.
• Biofilm formation was evaluated in the presence and absence of amyloid inhibitors and in S. mutans mutants lacking sortase.

Main Results:

• The S. mutans P1 adhesin was confirmed as an amyloid-forming protein.
• Amyloid structures were detected in human dental plaque and produced by S. mutans strains.
• Inhibition of amyloid formation, including by sortase-deficient mutants, significantly impaired S. mutans biofilm formation.

Conclusions:

• Streptococcus mutans is an amyloid-forming bacterium.
• Amyloidogenesis is a significant contributor to biofilm formation in Streptococcus mutans.
• Targeting amyloid formation presents a potential strategy for preventing dental caries.