Molecular Basis of Gamma Delta TCR Ligand Recognition

描述(由申请人提供)：虽然伽玛德尔塔(Gammadelta)T细胞受体代表了我们在适应性免疫中的第三种抗原受体，与抗体和AlphGamma T细胞受体一样，但它们的结构生物学、配体特异性和功能尚不清楚。然而，新出现的功能研究指出，在抵御癌症和病原体以及维持宿主内环境稳定方面发挥着重要作用。Gammadelta TCR使用DNA重排产生潜在的比抗体或AA TCR更大的组合多样性，但对于这种多样性是否用于特定的抗原识别，或者生殖系片段是否足以实现Gammadelta TCR的功能，仍存在争议。此外，与AA TCR不同，Gammadelta TCR可以在没有抗原处理的情况下识别MHC样和非MHC配体，类似于抗体/抗原识别。Gammadelta TCR是以类似于Alphabeta TCR与多肽-MHC相互作用的方式识别它们的配体，还是像在抗体/抗原复合体中看到的那样与多种识别溶液相互作用？目前还没有关于Gammadelta TCR与其配体相互作用的结构信息。这项应用的广泛目标是开始阐明Gammadelta TCR识别配体的分子和结构原理。我们的目标是表达、生化表征和确定Gammadelta TCR与蛋白质配体的配合物的X射线晶体结构，同时进行协作功能研究，以了解我们发现的免疫学相关性。我们在结构上的努力集中在一个功能完善的Gammadelta TCR系统上，即G8 Gammadelta TCR与非经典MHC T22和T10的相互作用。与Y.-h教授合作。钱，我们还将表达新的Gammadelta TCR的重组形式，并定义经典和非经典MHC的特异性，以询问是否存在MHC样配体的普遍收敛的Gammadelta识别模式。最后，我们将开始研究Gammadelta TCR识别非MHC蛋白抗原的结构基础是否与78 TCR识别MHC样抗原有根本不同。

DESCRIPTION (provided by applicant): Although gamma delta (gammadelta) T cell receptors represent our third lineage of antigen receptors in adaptive immunity, along with antibodies and alphgamma T cell receptors, their structural biology, ligand specificity, and function is poorly understood. Yet, emerging functional studies point to important roles in defense against cancers and pathogens, and the maintenance of host homeostasis. Gammadelta TCR use DNA rearrangement to generate potentially greater combinatorial diversity than antibodies or aa TCR, but controversy persists about whether this diversity is used for specific antigen recognition, or whether the germline segments are sufficient for gammadelta TCR function (2). Also, unlike aa TCR, gammadelta TCR can recognize both MHC-like and non-MHC ligands in the absence of antigen processing, similar to antibody/antigen recognition. Do gammadelta TCR recognize their ligands in a convergent manner reminiscent of alphabeta TCR interactions with peptide-MHC, or with a diversity of recognition solutions as seen in antibody/antigen complexes? Currently there is no structural information on the interactions of gammadelta TCR with their ligands. The broad goals of this application are to begin to elucidate the molecular and structural principles of ligand recognition by the gammadelta TCR. We aim to express, biochemically characterize, and determine the x-ray crystal structures of gammadelta TCR complexes with protein ligands, in companion with collaborative functional studies to understand the immunological relevance of our findings. We are focusing our structural efforts on a functionally well-characterized gammadelta TCR system, the interaction of the G8 gammadelta TCR with the non-classical MHC T22 and T10. In collaboration with Prof. Y.-h. Chien, we will also express recombinant forms of new gammadelta TCR with defined specificities for classical and non-classical MHC in order to ask whether there is a universally convergent gammadelta recognition mode of MHC-like ligands. Finally, we will begin to investigate whether the structural basis of gammadelta TCR recognition of non-MHC protein antigens is fundamentally different from 78 TCR recognition of MHC-like antigens.