M-like proteins of Streptococcus dysgalactiae
J Vasi1, L Frykberg, L E Carlsson
1Department of Microbiology, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden.
Infection and Immunity
|December 22, 1999
Summary
Researchers identified a novel fibrinogen-binding protein, DemA, in Streptococcus dysgalactiae, a key cause of bovine mastitis. The study suggests dmg and dem genes form a virulence regulon, similar to Streptococcus pyogenes' mga regulon.
Area of Science:
- Bacteriology
- Molecular Biology
- Veterinary Science
Background:
- Streptococcus dysgalactiae is a significant pathogen in bovine mastitis.
- Understanding its virulence factors is crucial for disease control.
Purpose of the Study:
- To identify and characterize novel virulence factors of Streptococcus dysgalactiae.
- To investigate the genetic regulation of these factors.
Main Methods:
- Construction of a phage display library against fibrinogen.
- Gene isolation, sequencing, and protein expression (DemA).
- Northern blot analysis to assess gene transcription under varying conditions.
Main Results:
- Isolation and characterization of the demA gene encoding the fibrinogen-binding protein DemA.
- DemA inhibits fibrinogen binding to S. dysgalactiae cells.
- Identification of dmgA and demA homologs (dmgB and demB) in another strain.
- Correlation between increased CO(2) levels, enhanced demB transcription, and fibrinogen binding in strain Epi9.
- Potential non-functional dmgA in strain 8215 due to insertion sequence element.
Conclusions:
- The dmg and dem genes in S. dysgalactiae likely constitute a regulon analogous to the mga regulon in S. pyogenes.
- This regulon potentially controls multiple virulence factors in S. dysgalactiae.
- Environmental factors like CO(2) may influence the expression of these virulence genes.
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