Molecular characterization of dextranase from Streptococcus rattus

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Dextranase enzymes play a role in dental caries by hydrolyzing dextran, a major component of dental plaque.
• Understanding the genetic and structural basis of dextranase in cariogenic bacteria is crucial for developing targeted interventions.

Purpose of the Study:

• To determine the complete nucleotide sequence of the dextranase gene from Streptococcus rattus ATCC19645.
• To characterize the biochemical properties and structural features of the S. rattus dextranase.

Main Methods:

• Gene sequencing to identify the dextranase open reading frame.
• Recombinant expression in Escherichia coli for protein purification.
• Enzyme activity assays to determine optimal pH and temperature.
• Amino acid sequence analysis to identify functional domains.

Main Results:

• The S. rattus dextranase gene sequence was determined, encoding a 920-amino acid protein (100,163 Da, pI 4.67).
• Purified recombinant S. rattus dextranase exhibited optimal activity at pH 5.0 and 40°C, similar to related species.
• Structural analysis revealed conserved and variable regions, including a catalytic domain, dextran-binding site, signal peptide, and cell wall sorting signal.

Conclusions:

• The S. rattus dextranase shares significant structural and functional similarities with dextranases from other cariogenic streptococci.
• These similarities suggest a conserved mechanism in dextran utilization and plaque formation among these bacteria.
• The characterized dextranase provides a target for further research into preventing dental caries.