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Streptococcus pyogenes type 12 M protein gene regulation by upstream sequences
J C Robbins1, J G Spanier, S J Jones
1Department of Microbiology, University of Minnesota, Minneapolis 55455.
Abstract:
A partial nucleotide sequence that included 1,693 base pairs of the M12 (emm12) gene of group A streptococci (strain CS24) and adjacent upstream DNA was determined. Type 12 M protein-specific mRNA of strain CS24 is transcribed from two promoters (P1 and P3) separated by 30 bases. The transcription start sites of the emm12 gene were located more than 400 bases downstream of a deletion that causes decreased M-protein gene transcription in strain CS64. Deletion analysis of M protein-expressing plasmids indicated that an upstream region greater than 1 kilobase is required for M-protein gene expression. The M-protein gene transcriptional unit appears to be monocistronic. Analysis of the emm12 DNA sequence revealed three major repeat regions. Two copies of each repeat, A and B, existed within the variable 5' end of the gene; repeat C demarcated the 5' end of the constant region shared by emm12 and emm6.
Insights
Group A Streptococcus M12 gene transcription is regulated by upstream DNA and multiple promoters. This study details the M12 gene sequence and its regulatory elements, crucial for understanding M protein expression.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Group A Streptococcus (GAS) produces M protein, a key virulence factor.
- The emm12 gene encodes the Type 12 M protein, important for GAS pathogenesis.
- Understanding M protein gene regulation is vital for developing targeted therapies.
Purpose of the Study:
- To determine the nucleotide sequence of the emm12 gene and adjacent upstream DNA in GAS strain CS24.
- To identify regulatory elements controlling M12 gene transcription.
- To elucidate the transcriptional unit and structural features of the emm12 gene.
Main Methods:
- Partial nucleotide sequencing of the emm12 gene and upstream DNA.
- Analysis of M protein-specific mRNA transcription start sites.
- Deletion analysis of M protein-expressing plasmids.
- DNA sequence analysis to identify repeat regions.
Main Results:
- A 1,693 base pair sequence of the emm12 gene and upstream DNA was determined.
- Transcription initiates from two promoters (P1 and P3).
- An upstream region exceeding 1 kilobase is necessary for M-protein gene expression.
- The emm12 gene is monocistronic and contains three major repeat regions (A, B, and C).
Conclusions:
- The emm12 gene has complex transcriptional regulation involving upstream DNA and multiple promoters.
- Specific repeat regions within the emm12 gene contribute to its structure and regulation.
- Findings provide insights into the molecular basis of M protein expression in Group A Streptococcus.