title: Structure of the superantigen staphylococcal enterotoxin B in complex with TCR and peptide-MHC demonstrates absence of TCR-peptide contacts.
abstract: Superantigens are immune-stimulatory toxins produced by Staphylococcus aureus, which are able to interact with host immune receptors to induce a massive release of cytokines, causing toxic shock syndrome and possibly death. In this article, we present the x-ray structure of staphylococcal enterotoxin B (SEB) in complex with its receptors, the TCR and MHC class II, forming a ternary complex. The structure, in combination with functional analyses, clearly shows how SEB adopts a wedge-like position when binding to the β-chain of TCR, allowing for an interaction between the α-chain of TCR and MHC. Furthermore, the binding mode also circumvents contact between TCR and the peptide presented by MHC, which enables SEB to initiate a peptide-independent activation of T cells.
authors.affiliation: Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden.
authors.forename: Karin E J
authors.initials: KE
authors.lastname: Rödström
authors.affiliation: Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Elbing
authors.affiliation: Department of Experimental Medical Science, Lund University, 221 84 Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Lindkvist-Petersson
mesh_terms: D002478:Cells, Cultured; D003460:Crystallization; D018360:Crystallography, X-Ray; D004768:Enterotoxins / Q000737:chemistry*; D000949:Histocompatibility Antigens Class II / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D008958:Models, Molecular; D011485:Protein Binding / Q000276:immunology; D017433:Protein Structure, Secondary; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry* / Q000648:ultrastructure; D013211:Staphylococcus aureus / Q000276:immunology*; D018089:Superantigens / Q000737:chemistry* / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D004768:Enterotoxins; D000949:Histocompatibility Antigens Class II; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens; C031818:enterotoxin B, staphylococcal