title: Structure of Staphylococcal Enterotoxin E in Complex with TCR Defines the Role of TCR Loop Positioning in Superantigen Recognition.
abstract: 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.
authors.affiliation: Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden.
authors.forename: Karin E J
authors.initials: KE
authors.lastname: Rödström
authors.affiliation: Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden.
authors.forename: Paulina
authors.initials: P
authors.lastname: Regenthal
authors.affiliation: Department of Experimental Medical Science, Lund University, BMC C13, 22 184, Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Lindkvist-Petersson
mesh_terms: D018360:Crystallography, X-Ray; D004768:Enterotoxins / Q000378:metabolism*; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000276:immunology; D018089:Superantigens / Q000378:metabolism*
chemical_list: D004768:Enterotoxins; D011948:Receptors, Antigen, T-Cell; D018089:Superantigens; C049463:enterotoxin E, Staphylococcal