Modulation of glucan-binding protein activity in streptococci by fluoride

Area of Science:

• Microbiology
• Biochemistry
• Oral Health

Background:

• Streptococcus sobrinus produces glucan-binding proteins (GBPs) crucial for dental plaque formation.
• Fluoride is widely used in water fluoridation for caries prevention.
• The specific mechanisms of fluoride's effects on oral bacteria are not fully understood.

Purpose of the Study:

• To investigate the impact of fluoride on glucan-binding lectin (GBL) activity and other GBPs in Streptococcus sobrinus.
• To elucidate the role of manganous ions in mediating fluoride's effects on these bacterial proteins.

Main Methods:

• Bacterial growth in media with varying fluoride concentrations.
• Detection of GBL and other GBPs using enhanced chemiluminescence (ECL) and Western blotting.
• Assessment of glucosyltransferase (GTF) activity.
• Evaluation of fluoride's effects in the presence of manganous ions.

Main Results:

• Fluoride significantly reduced GBL activity by approximately 1.5 mM.
• Subinhibitory fluoride concentrations decreased other GBPs but did not affect GTFs.
• The inhibitory effects of fluoride on GBPs were abrogated by manganous ions.

Conclusions:

• Fluoride interferes with the expression or activity of key glucan-binding proteins in Streptococcus sobrinus.
• Manganous ions appear to counteract fluoride's inhibitory effects, possibly by influencing protein metabolism.
• This study suggests that fluoride's impact on GBPs is a significant mechanism of action for fluoridated water in preventing dental caries.