Abstract
Superantigens (SAGs) are a class of immunostimulatory proteins of bacterial or viral origin that activate T cells by binding to the V beta domain of the T cell antigen receptor (TCR). The three-dimensional structure of the complex between a TCR beta chain (mouse V beta8.2) and the SAG staphylococcal enterotoxin B (SEB) at 2.4 A resolution reveals why SEB recognizes only certain V beta families, as well as why only certain SAGs bind mouse V beta8.2. Models of the TCR-SEB-peptide/MHC class II complex indicate that V alpha interacts with the MHC beta chain in the TCR-SAG-MHC complex. The extent of the interaction is variable and is largely determined by the geometry of V alpha/V beta domain association. This variability can account for the preferential expression of certain V alpha regions among T cells reactive with SEB.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Crystallography, X-Ray
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Enterotoxins / chemistry*
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Enterotoxins / immunology
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Histocompatibility Antigens Class II / chemistry
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Histocompatibility Antigens Class II / immunology
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Mice
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Models, Molecular
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Peptide Fragments / chemistry*
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Peptide Fragments / immunology
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Peptides / chemistry
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Peptides / immunology
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Protein Conformation*
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Receptors, Antigen, T-Cell, alpha-beta / chemistry*
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Receptors, Antigen, T-Cell, alpha-beta / immunology
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Receptors, Antigen, T-Cell, alpha-beta / physiology
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Staphylococcus aureus / immunology*
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Superantigens / chemistry*
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Superantigens / immunology
Substances
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Enterotoxins
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Histocompatibility Antigens Class II
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Peptide Fragments
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Peptides
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Receptors, Antigen, T-Cell, alpha-beta
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Superantigens
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T-cell receptor Vbeta 8.2
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enterotoxin B, staphylococcal