A mutational analysis of the binding of staphylococcal enterotoxins B and C3 to the T cell receptor beta chain and major histocompatibility complex class II.
A mutational analysis of the binding of staphylococcal enterotoxins B and C3 to the T cell receptor beta chain and major histocompatibility complex class II.
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DOI：
10.1084/jem.187.6.823
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发表时间：
1998-03-16
期刊：
影响因子：
--
通讯作者：
Mariuzza RA
中科院分区：
文献类型：
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作者：
Leder L;Llera A;Lavoie PM;Lebedeva MI;Li H;Sékaly RP;Bohach GA;Gahr PJ;Schlievert PM;Karjalainen K;Mariuzza RA
T细胞受体（TCR）β链（小鼠Vβ8.2Jβ2.1Cβ1）和超抗原（SAG）葡萄球菌肠毒素C3（SEC 3）之间复合物的三维结构最近已被确定为3.5 μ m分辨率。为了评估单个SAG残基对稳定β-SEC 3复合物的实际贡献，以及研究SAG对TCR和MHC的亲和力与其活化T细胞的能力之间的关系，我们测量了一组SEC 3和葡萄球菌肠毒素B（SE B）突变体与可溶性重组TCR β链和人MHC II类分子HLA-DR 1的结合。通过沉降平衡和/或表面等离子体检测来确定亲和力，而使用来自重排缺陷TCR转基因小鼠的T细胞来评估促有丝分裂效价。我们发现，SAG对TCR的亲和力与其生物活性之间存在明确而简单的关系：SEC 3或SEB的特定突变体与TCR β链的结合越紧密，其刺激T细胞的能力越强。我们还发现，在确定促有丝分裂效力中，TCR-SAG和SAG-MHC相互作用之间存在相互作用，使得SAG对MHC的亲和力的小幅增加可以克服SAG对TCR的亲和力的大幅降低。最后，我们观察到那些对稳定β-SEC 3复合物做出最大能量贡献的SEC 3残基（“热点”残基）在与小鼠Vβ8.2反应的肠毒素中是严格保守的，从而为理解为什么在这些位置具有其他残基的SAG显示不同的Vβ结合特异性提供了基础。
The three-dimensional structure of the complex between a T cell receptor (TCR) β chain (mouse Vβ8.2Jβ2.1Cβ1) and the superantigen (SAG) staphylococcal enterotoxin C3 (SEC3) has been recently determined to 3.5 Å resolution. To evaluate the actual contribution of individual SAG residues to stabilizing the β–SEC3 complex, as well as to investigate the relationship between the affinity of SAGs for TCR and MHC and their ability to activate T cells, we measured the binding of a set of SEC3 and staphylococcal enterotoxin B (SEB) mutants to soluble recombinant TCR β chain and to the human MHC class II molecule HLA-DR1. Affinities were determined by sedimentation equilibrium and/or surface plasmon detection, while mitogenic potency was assessed using T cells from rearrangement-deficient TCR transgenic mice. We show that there is a clear and simple relationship between the affinity of SAGs for the TCR and their biological activity: the tighter the binding of a particular mutant of SEC3 or SEB to the TCR β chain, the greater its ability to stimulate T cells. We also find that there is an interplay between TCR–SAG and SAG–MHC interactions in determining mitogenic potency, such that a small increase in the affinity of a SAG for MHC can overcome a large decrease in the SAG's affinity for the TCR. Finally, we observe that those SEC3 residues that make the greatest energetic contribution to stabilizing the β–SEC3 complex (“hot spot” residues) are strictly conserved among enterotoxins reactive with mouse Vβ8.2, thereby providing a basis for understanding why SAGs having other residues at these positions show different Vβ-binding specificities.