1ty2
From Proteopedia
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Crystal structure of the streptococcal pyrogenic exotoxin J (SPE-J)
Overview
The protein toxins known as superantigens (SAgs), which are expressed, primarily by the pathogenic bacteria Staphylococcus aureus and, Streptococcus pyogenes, are highly potent immunotoxins with the ability to, cause serious human disease. These SAgs share a conserved fold but quite, varied activities. In addition to their common role of cross-linking, T-cell receptors (TCRs) and major histocompatibility complex class II, (MHC-II) molecules, some SAgs can cross-link MHC-II, using diverse, mechanisms. The crystal structure of the streptococcal superantigen, streptococcal pyrogenic exotoxin J (SPE-J) has been solved at 1.75 A, resolution (R = 0.209, R(free) = 0.240), both with and without bound, Zn(2+). The structure displays the canonical two-domain SAg fold and a, zinc-binding site that is shared by a subset of other SAgs. Most, importantly, in concentrated solution and in the crystal, SPE-J forms, dimers. These dimers, which are present in two different crystal, environments, form via the same face that is used for TCR binding in other, SAgs. Site-directed mutagenesis shows that this face is also used for TCR, binding SPE-J. We infer that SPE-J cross-links TCR and MHC-II as a monomer, but that dimers may form on the antigen-presenting cell surface, cross-linking MHC-II and eliciting intracellular signaling.
About this Structure
1TY2 is a Single protein structure of sequence from Streptococcus pyogenes with ZN as ligand. Full crystallographic information is available from OCA.
Reference
Crystallographic and mutational data show that the streptococcal pyrogenic exotoxin J can use a common binding surface for T-cell receptor binding and dimerization., Baker HM, Proft T, Webb PD, Arcus VL, Fraser JD, Baker EN, J Biol Chem. 2004 Sep 10;279(37):38571-6. Epub 2004 Jul 7. PMID:15247241
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