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Staphylococcal protein A binding to VH3 encoded immunoglobulins
1Department of Microbiology, University of Texas, Southwestern Medical Center, Dallas 75235, USA.
International Reviews of Immunology
|January 1, 1997
Summary
Staphylococcal protein A (SPA) binds to human VH3 antibodies. Residues in FR1, CDR2, and FR3 are simultaneously required for this binding interaction, with alterations disrupting SPA binding.
Area of Science:
- Immunology
- Structural Biology
- Protein-Antibody Interactions
Background:
- Staphylococcal protein A (SPA) is a B-cell superantigen.
- SPA specifically targets the variable region of human VH3 encoded antibodies.
Purpose of the Study:
- To identify the specific VH3 regions involved in the interaction with SPA.
- To elucidate the structural requirements for SPA binding to VH3 antibodies.
Main Methods:
- Production of mutant antibodies using the baculovirus expression system.
- Analysis of SPA binding patterns following region-specific mutations and exchanges between human and mouse antibodies.
Main Results:
- A single amino acid change in CDR2 converted a nonbinding rheumatoid factor to an SPA binder.
- Residues in Framework Region 1 (FR1), Complementarity-Determining Region 2 (CDR2), and Framework Region 3 (FR3) were implicated in SPA binding.
- Simultaneous presence and integrity of FR1, CDR2, and FR3 are essential for SPA binding; alteration of any single region severely disrupts binding.
Conclusions:
- The interaction between SPA and VH3 antibodies is complex, requiring contributions from multiple distinct regions.
- FR1, CDR2, and FR3 collectively mediate SPA binding to VH3 antibodies.
- Understanding these interaction sites is crucial for antibody engineering and therapeutic development.