1qil
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INACTIVE MUTANT TOXIC SHOCK SYNDROME TOXIN-1 AT 2.5 A
OverviewOverview
Toxic shock syndrome toxin-1 (TSST-1) is one of a family of staphylococcal, exotoxins recognized as microbial superantigens. The toxin plays a, dominant role in the genesis of toxic shock in humans through a massive, activation of the immune system. This potentially lethal illness occurs as, a result of the interaction of TSST-1 with a significant proportion of the, T-cell repertoire. TSST-1, like other superantigens, can bind directly to, class II major histocompatibility (MHC class II) molecules prior to its, interaction with entire families of V beta chains of the T-cell receptor, (TCR). The three-dimensional structure of a mutant (His-135-Ala) TSST-1, was compared with the structure of the native (wild-type) TSST-1 at 2.5 A, resolution. The replacement of His 135 of TSST-1 with an Ala residue, results in the loss of T-cell mitogenicity and toxicity in experimental, animals. This residue, postulated to be directly involved in the toxin-TCR, interactions, is located on the major helix alpha 2, which forms the, backbone of the molecule and is exposed to the solvent. In the molecular, structure of the mutant toxin, the helix alpha 2 remains unaltered, but, the His to Ala modification causes perturbations on the neighboring helix, alpha 1 by disrupting helix-helix interactions. Thus, the effects on TCR, binding of the His 135 residue could actually be mediated, wholly or in, part, by the alpha 1 helix.
About this StructureAbout this Structure
1QIL is a Single protein structure of sequence from Staphylococcus aureus. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a biologically inactive mutant of toxic shock syndrome toxin-1 at 2.5 A resolution., Papageorgiou AC, Quinn CP, Beer D, Brehm RD, Tranter HS, Bonventre PF, Acharya KR, Protein Sci. 1996 Aug;5(8):1737-41. PMID:8844860
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