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Sequence analysis of scrA and scrB from Streptococcus sobrinus 6715
Y Y Chen1, L N Lee, D J LeBlanc
1Department of Microbiology, University of Texas Health Science Center at San Antonio 78284-7758.
Infection and Immunity
|June 1, 1993
Summary
The nucleotide sequences of Streptococcus sobrinus 6715 scrA and scrB genes were determined. These genes encode key enzymes in sucrose metabolism, showing homology to related proteins in other bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Streptococcus sobrinus is a key bacterium in dental caries.
- Understanding its metabolic pathways, like sucrose utilization, is crucial.
Purpose of the Study:
- To determine the complete nucleotide sequences of the Streptococcus sobrinus 6715 scrA and scrB genes.
- To analyze the encoded proteins and their functional domains.
Main Methods:
- Nucleotide sequencing of scrA and scrB genes.
- Primer extension analysis to determine transcriptional initiation sites.
- Bioinformatic analysis of predicted amino acid sequences and protein homology.
Main Results:
- The complete nucleotide sequences of scrA and scrB were determined.
- scrA encodes a hydrophobic sucrose-specific enzyme II (66,529 Da), and scrB encodes a hydrophilic sucrose-6-phosphate hydrolase (54,501 Da).
- Significant homology was found with genes from Streptococcus mutans and other bacterial species, indicating conserved functions and protein domains.
Conclusions:
- The scrA and scrB genes are divergently transcribed with overlapping promoter regions.
- The enzyme IIScr protein contains domains homologous to other enzyme IIs and IIIGlc/IIBgl, suggesting a covalently linked enzyme IIScr-IIIScr structure.
- The scrB gene product shows homology to sucrases from other bacteria, highlighting conserved roles in sucrose hydrolysis.