Binding forces of Streptococcus mutans P1 adhesin

Area of Science:

• Microbiology
• Biophysics
• Biochemistry

Background:

• Streptococcus mutans is a primary cause of dental caries.
• The P1 adhesin mediates bacterial adhesion to salivary agglutinin (SAG).
• Understanding P1's binding mechanisms is crucial for developing anti-adhesion therapies.

Purpose of the Study:

• To quantify the nanoscale forces driving P1-mediated adhesion to SAG.
• To investigate the cooperative binding mechanisms of P1.
• To explore P1 interactions with other matrix proteins and substrates.

Main Methods:

• Atomic force microscopy-based single-molecule force spectroscopy.
• Single-cell force spectroscopy.
• Analysis of P1 interactions with SAG, fibronectin, collagen, and hydrophobic/hydrophilic substrates.

Main Results:

• Single P1 molecules bind SAG with weak forces (~50 pN).
• Single S. mutans cells exhibit strong (~500 pN), long-range (~6000 nm) adhesion to SAG via cooperative P1 binding.
• P1 also interacts with fibronectin and collagen, and hydrophobic substrates.

Conclusions:

• Cooperative binding of multiple P1 adhesins to SAG explains strong, long-range bacterial adhesion.
• P1's multifunctional binding properties are explained by its strong forces, cooperativity, and broad specificity.
• The methodology provides a valuable approach for studying bacterial adhesins and developing anti-adhesion therapies.