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Type M12 protein from Streptococcus pyogenes is a receptor for IgG3
D S Retnoningrum1, A Podbielski, P P Cleary
1Department of Microbiology, University of Minnesota, Minneapolis 55455.
Journal of Immunology (Baltimore, Md. : 1950)
|March 15, 1993
Summary
Streptococcus pyogenes M12 protein acts as a human IgG3 receptor. This study identified the specific IgG3 binding domain within the M12 protein, aiding in understanding bacterial immune evasion.
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Streptococcus pyogenes is a significant human pathogen.
- Understanding bacterial immune evasion mechanisms is crucial for developing therapeutics.
Purpose of the Study:
- To identify and characterize the human IgG3 binding protein expressed by Streptococcus pyogenes serotype M12.
- To determine the specific domain responsible for IgG3 binding.
Main Methods:
- Western blot analysis was used to assess protein size and binding activity.
- Polymerase chain reaction (PCR) and subcloning were employed to express the M12 protein in Escherichia coli.
- Deletion analyses were performed to map the IgG3 binding domain.
Main Results:
- The M12 protein from Streptococcus pyogenes serotype M12 was confirmed to bind human IgG3.
- Recombinant expression in E. coli demonstrated the IgG3 binding activity of the M12 protein.
- Deletion studies localized the IgG3 binding domain to a 200 amino acid internal fragment.
Conclusions:
- The M12 protein of Streptococcus pyogenes functions as an IgG3 receptor.
- The identified binding domain is distinct from the Protein G binding site.
- This finding contributes to understanding how S. pyogenes evades the human immune system.