A novel loop domain in superantigens extends their T cell receptor recognition site.

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TitleA novel loop domain in superantigens extends their T cell receptor recognition site.
Publication TypeJournal Article
Year of Publication2007
AuthorsGünther, S, Varma, AK, Moza, B, Kasper, KJ, Wyatt, AW, Zhu, P, Rahman, AKMNur-ur, Li, Y, Mariuzza, RA, McCormick, JK, Sundberg, EJ
JournalJ Mol Biol
Date Published2007 Aug 3
KeywordsBacterial Proteins, Crystallography, X-Ray, Enterotoxins, Humans, Models, Molecular, Protein Binding, Protein Structure, Tertiary, Receptors, Antigen, T-Cell, alpha-beta, Signal Transduction, Staphylococcus aureus, Superantigens

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 alpha3-beta8 loop, a unique approximately 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 hVbeta5.1 domain. SEK adopts a unique TCR binding orientation relative to other SAG-TCR complexes, which results in the alpha3-beta8 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 Vbeta domain specificity of SEK and other group V SAGs.

Alternate JournalJ. Mol. Biol.
PubMed ID17560605
PubMed Central IDPMC2949350
Grant ListAI036900 / AI / NIAID NIH HHS / United States
R21 AI055882-03 / AI / NIAID NIH HHS / United States
R37 AI036900-12 / AI / NIAID NIH HHS / United States