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Protein F, a fibronectin-binding protein, is an adhesin of the group A streptococcus Streptococcus pyogenes
1Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110-1093.
Abstract:
Binding to fibronectin has been suggested to play an important role in adherence of the group A streptococcus Streptococcus pyrogenes to host epithelial cells; however, the identity of the streptococcal fibronectin receptor has been elusive. Here we demonstrate that the fibronectin-binding property of S. pyogenes is mediated by protein F, a bacterial surface protein that binds fibronectin at high affinity. The gene encoding protein F (prtF) produced a functional fibronectin-binding protein in Escherichia coli. Insertional mutagenesis of the cloned gene generated a mutation that resulted in the loss of fibronectin-binding activity. When this mutation was introduced into the S. pyrogenes chromosome by homologous recombination with the wild-type allele, the resulting strains no longer produced protein F and lost their ability to bind fibronectin. The mutation could be complemented by prtF introduced on a plasmid. Mutants lacking protein F had a much lower capacity to adhere to respiratory epithelial cells. These results demonstrate that protein F is an important adhesin of S. pyogenes.
Insights
Group A Streptococcus uses protein F to bind fibronectin, aiding adherence to host cells. This protein is crucial for bacterial adhesion to respiratory epithelial cells.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Group A Streptococcus (Streptococcus pyogenes) adherence to host epithelial cells is critical for infection.
- The specific bacterial adhesin responsible for fibronectin binding in S. pyogenes remained unidentified.
Purpose of the Study:
- To identify the fibronectin receptor of Streptococcus pyogenes.
- To investigate the role of this receptor in bacterial adherence to host cells.
Main Methods:
- Cloning and expression of the putative fibronectin-binding protein gene (prtF) in Escherichia coli.
- Generating insertional mutants of prtF in S. pyogenes via homologous recombination.
- Assessing fibronectin-binding activity and adherence to epithelial cells in wild-type and mutant strains.
Main Results:
- Protein F, encoded by prtF, was identified as a high-affinity fibronectin-binding protein.
- Mutants lacking protein F exhibited significantly reduced fibronectin-binding activity.
- Deletion of protein F impaired S. pyogenes adherence to respiratory epithelial cells.
Conclusions:
- Protein F is the primary fibronectin receptor of Streptococcus pyogenes.
- Protein F functions as a key adhesin mediating bacterial attachment to host epithelial cells.
- Targeting protein F could be a strategy to prevent S. pyogenes infections.