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Staphylococcus aureus expresses a cell surface protein that binds both IgG and beta2-glycoprotein I
Microbiology (Reading, England)
|April 17, 1999
Summary
Staphylococcus aureus protein Sbi binds beta2-glycoprotein I (beta2-GPI), a serum component. This binding involves a distinct 57-amino acid domain, separate from its IgG-binding site, and varies between bacterial strains.
Area of Science:
- Microbiology
- Immunology
- Protein Biochemistry
Background:
- Staphylococcus aureus possesses protein Sbi, a known IgG-binding protein.
- Previous studies suggested protein Sbi interacts with additional serum components beyond IgG.
Purpose of the Study:
- To identify the serum component bound by protein Sbi.
- To characterize the binding domain and cell surface expression of protein Sbi's beta2-GPI binding activity.
Main Methods:
- Affinity purification using immobilized protein Sbi.
- Shotgun phage display to identify minimal binding domains.
- Analysis of protein Sbi expression on bacterial cell surfaces.
Main Results:
- Beta2-glycoprotein I (beta2-GPI), also known as apolipoprotein H, was identified as the serum component bound by protein Sbi.
- A 57-amino acid region, distinct from the IgG-binding domain, mediates beta2-GPI binding.
- Protein Sbi expression and beta2-GPI binding activity vary among different Staphylococcus aureus strains.
Conclusions:
- Protein Sbi binds beta2-GPI via a specific, separate domain.
- The cell surface expression of this binding activity is strain-dependent in Staphylococcus aureus.