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Single-molecule imaging of interaction between dextran and glucosyltransferase from Streptococcus sobrinus
1Laboratory of Molecular Enzymology, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan.
Journal of Bacteriology
|January 29, 2000
Summary
Researchers directly observed Streptococcus sobrinus glucosyltransferase I (GTF) interacting with dextran using microscopy. Sucrose was found to accelerate GTF dissociation from dextran, though at a slower rate than GTF
Area of Science:
- Microbiology
- Biochemistry
- Biophysics
Background:
- Streptococcus sobrinus produces glucosyltransferase I (GTF), an enzyme crucial for dental plaque formation via dextran synthesis.
- Understanding the molecular interactions between GTF and dextran is key to developing strategies to prevent biofilm formation.
Purpose of the Study:
- To directly visualize and quantify the dynamic interactions between GTF and dextran.
- To investigate the effect of sucrose on the GTF-dextran binding kinetics.
Main Methods:
- Total internal reflection fluorescence microscopy (TIRFm) was employed to image individual Tetramethylrhodamine (TMR)-labeled GTF or dextran molecules.
- Dwell time analysis was performed on imaged molecules to determine interaction kinetics.
- Kinetic rates were measured at specific pH and temperature conditions, with and without sucrose.
Main Results:
- Direct observation revealed dynamic association and dissociation of GTF with dextran, and vice versa.
- Dwell time histograms indicated that the GTF-dextran interaction follows apparent first-order kinetics.
- Sucrose accelerated the dissociation rate of GTF from dextran from 9.2 s⁻¹ to 13.3 s⁻¹ at pH 6.8 and 25°C.
Conclusions:
- The study provides direct kinetic evidence of GTF-dextran interactions at the single-molecule level.
- Sucrose influences GTF-dextran binding by promoting dissociation, but this effect is slower than GTF's catalytic activity.
- These findings offer insights into the mechanisms of dextran synthesis and potential targets for anti-adhesion therapies.
