The superantigen staphylococcal enterotoxin A (SEA) binds to major histocompatibility complex (MHC) class II molecules at two sites on either side of the peptide groove. Two separate but cooperative interactions to the human class II molecule HLA-DR1 were detected. The first high affinity interaction to the DR1 beta chain is mediated by a zinc atom coordinated by H187, H225, and D227 in SEA and H81 in the polymorphic DR1 beta chain. The second low affinity site is to the DR1 alpha chain analogous to SEB binding and is mediated by residue F47 in SEA. Binding of one SEA to the DR1 beta chain enhances the binding of a second SEA molecule to the DR1 alpha chain. The zinc site is on the opposite side of the SEA molecule from residue F47 so that one SEA molecule can readily bind two class II molecules. Both binding sites on SEA are required for maximal activity. Thus, unlike, SEB, SEA requires two separate binding sites for optimal activity, which may allow it to stabilize SEA interaction with T cell receptors, as well as to activate the antigen-presenting cell by cross-linking MHC class II.
Article|
September 01 1995
Staphylococcal enterotoxin A has two cooperative binding sites on major histocompatibility complex class II.
K R Hudson,
K R Hudson
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
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R E Tiedemann,
R E Tiedemann
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
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R G Urban,
R G Urban
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
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S C Lowe,
S C Lowe
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
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J L Strominger,
J L Strominger
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
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J D Fraser
J D Fraser
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
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K R Hudson
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
R E Tiedemann
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
R G Urban
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
S C Lowe
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
J L Strominger
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
J D Fraser
Department of Molecular Medicine, University of Auckland School of Medicine, New Zealand.
Online ISSN: 1540-9538
Print ISSN: 0022-1007
J Exp Med (1995) 182 (3): 711–720.
Citation
K R Hudson, R E Tiedemann, R G Urban, S C Lowe, J L Strominger, J D Fraser; Staphylococcal enterotoxin A has two cooperative binding sites on major histocompatibility complex class II.. J Exp Med 1 September 1995; 182 (3): 711–720. doi: https://doi.org/10.1084/jem.182.3.711
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