کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2188014 | 1096149 | 2007 | 12 صفحه PDF | دانلود رایگان |
Superantigens (SAGs) interact with host immune receptors to induce a massive release of inflammatory cytokines that can lead to toxic shock syndrome and death. Bacterial SAGs can be classified into five distinct evolutionary groups. Group V SAGs are characterized by the α3-β8 loop, a unique ∼ 15 amino acid residue extension that is required for optimal T cell activation. Here, we report the X-ray crystal structures of the group V SAG staphylococcal enterotoxin K (SEK) alone and in complex with the TCR hVβ5.1 domain. SEK adopts a unique TCR binding orientation relative to other SAG–TCR complexes, which results in the α3-β8 loop contacting the apical loop of framework region 4, thereby extending the known TCR recognition site of SAGs. These interactions are absolutely required for TCR binding and T cell activation by SEK, and dictate the TCR Vβ domain specificity of SEK and other group V SAGs.
Journal: Journal of Molecular Biology - Volume 371, Issue 1, 3 August 2007, Pages 210–221