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Publication Abstract from PubMed

Bacterial superantigens are potent T-cell stimulatory protein molecules produced by Staphylococcus aureus and Streptococcus pyogenes. Their superantigenic activity can be attributed to their ability to cross-link major histocompatibility complex class II molecules with T-cell receptors (TCRs) to form a tri-molecular complex. Each superantigen is known to interact with a specific V(beta) element of TCR. Staphylococcal enterotoxin B (SEB, a superantigen), a primary cause of food poisoning, is also responsible for a significant percentage of non-menstrual associated toxic shock syndrome in patients with a variety of staphylococcal infections. Structural studies have elucidated a binding cavity on the toxin molecule essential for TCR binding. To understand the crucial residues involved in binding, mutagenesis analysis was performed. Our analysis suggest that mutation of a conserved residue Thr(112) to Ser (T112S) in the binding cavity induces a selective reduction in the affinity for binding one TCR V(beta) family and can be attributed to the structural differences in the native and mutant toxins. We present a detailed comparison of the mutant structure determined at 2.0 A with the previously reported native SEB and SEB-TCR V(beta) complex structures.

Structural and functional role of threonine 112 in a superantigen Staphylococcus aureus enterotoxin B.,Baker MD, Papageorgiou AC, Titball RW, Miller J, White S, Lingard B, Lee JJ, Cavanagh D, Kehoe MA, Robinson JH, Acharya KR J Biol Chem. 2002 Jan 25;277(4):2756-62. Epub 2001 Nov 9. PMID:11704673^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.