Structure of Staphylococcal Enterotoxin E in Complex with TCR Defines the Role of TCR Loop Positioning in Superantigen Recognition

T cells are crucial players in cell-mediated immunity. The specificity of their receptor, the T cell receptor (TCR), is central for the immune system to distinguish foreign from host antigens. Superantigens are bacterial toxins capable of inducing a toxic immune response by cross-linking the TCR and...

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Bibliographic Details
Published in:	PloS one 2015-07, Vol.10 (7), p.e0131988
Main Authors:	Rödström, Karin E J, Regenthal, Paulina, Lindkvist-Petersson, Karin
Format:	Article
Language:	eng
Subjects:	Antigens Bacteria Basic Medicine Bioinformatics Cell-mediated immunity Chains Chromatography Complex formation Crosslinking Crystal structure Crystallography, X-Ray Enterotoxins - metabolism Glycerol Humans Immune response Immune system Immunity Immunity, Cellular - immunology Immunologi inom det medicinska området Immunology Immunology in the medical area Lymphocytes Lymphocytes T Major histocompatibility complex Medical and Health Sciences Medicin och hälsovetenskap Medicinska och farmaceutiska grundvetenskaper Peptides Protein Conformation Proteins Receptors, Antigen, T-Cell - metabolism Staphylococcal enterotoxin E Staphylococcus aureus - immunology Superantigens Superantigens - metabolism T cell receptors T cells T-cell receptor Toxins
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Summary:	T cells are crucial players in cell-mediated immunity. The specificity of their receptor, the T cell receptor (TCR), is central for the immune system to distinguish foreign from host antigens. Superantigens are bacterial toxins capable of inducing a toxic immune response by cross-linking the TCR and the major histocompatibility complex (MHC) class II and circumventing the antigen specificity. Here, we present the structure of staphylococcal enterotoxin E (SEE) in complex with a human T cell receptor, as well as the unligated T cell receptor structure. There are clear structural changes in the TCR loops upon superantigen binding. In particular, the HV4 loop moves to circumvent steric clashes upon complex formation. In addition, a predicted ternary model of SEE in complex with both TCR and MHC class II displays intermolecular contacts between the TCR α-chain and the MHC, suggesting that the TCR α-chain is of importance for complex formation.
ISSN:	1932-6203 1932-6203