Molecular Principles of TCR Recognition and Activation by peptide-MHC

结构生物学阐明了AP TCR如何与多肽相互作用的几个一般原理。 MHC配体，但涉及识别和激活MHC配体的几个基本问题 TCR，请保持无人接听。首先，我们还不了解MHC TCR偏向的结构基础。是 在松散收敛的TCR/pMHC对角对接背后有一个识别码 方向，还是迄今为止在不同建筑群中看到的“脚印”？一种新的TCR/pMHC复合体 我们确定的结构表明可以解释的对接主题可能是有限的 通过对一系列相关络合物的结构研究。这些对接拓扑很可能是 在连接编码的TCR CDR3与多肽的相互作用和生殖系- 编码的可变区与MHC螺旋的相互作用。因此，我们正在为 结构研究，将分离出这些组成部分的每一个贡献。第二，范围有多大 TCR交叉反应性，以及TCR CDR构象灵活性在多大程度上发挥作用 扩充T细胞谱系？我们之前的研究表明，T细胞识别并不广泛 但有一种流行的观点认为，CDR3诱导的FIT是一种扩大 TCR认可的pMHC曲目。为了更好地理解构象蛋白的作用 在TCR/pMHC相互作用中的动力学，我们正在确定TCR和pMHC的结构，并解决 相互作用，使用核磁共振波谱(核磁共振)。最后，我们目前还不知道 TCR和CDS如何在TCR-CD3复合体中相互作用。TCR对pMHC的识别情况如何 在结构上传递给相关的CD3亚基，以便随后的信号传递？我们建议 重组纯化全长膜结合型TCR-CD3复合体 生物物理成像研究。总而言之，在本奖项的上一届任期内，我们发展得很稳健 TCR和多肽-MHC的表达方法现在使我们能够进行多学科的 使用X射线结晶学、核磁共振、多肽库、 噬菌体展示和电子显微镜(EM)。

Structural biology has elucidated several general principles for how the ap TCR interacts with peptide- MHC ligands, but several fundamental questions, pertaining to both the recognition and activation of the TCR, remain unanswered. First, we do not yet understand the structural basis of TCR bias for MHC. Is there a recognition code underlying the loosely convergent TCR/pMHC diagonal docking orientations, or "footprints" so far seen in the different complexes ? A recent TCR/pMHC complex structure we determined suggests there may be limited sets of docking motifs that could be elucidated through structural studies of a series of related complexes. These docking topologies are likely the result of a complex interplay between junctionally-encoded TCR CDR3 interactions with peptide, and the germline- encoded Variable region interactions with the MHC helices. Therefore, we are engineering molecules for structural studies that will isolate the contributions of each of these components. Second, what is the scope of TCR cross-reactivity, and to what extent does TCR CDR conformational flexibility play a role in expanding the T cell repertoire ? Our previous studies suggest that T cell recognition is not broadly promiscuous, and yet there is a prevailing notion that CDR3 induced fit is a mechanism to expand the repertoire of pMHC recognized by the TCR. In order to better understand the role of conformational dynamics in TCR/pMHC interactions, we are determining TCR and pMHC structures, and solution interactions, using Nuclear Magnetic Resonance spectroscopy (NMR). Finally, we currently do not know how TCR and CDS interact in the TCR-CD3 complex. How is recognition of pMHC by the TCR structurally communicated to the associated CD3 subunits for subsequent signaling ? We propose to reconstitute and purify a recombinant form of a full-length, membrane-bound TCR-CD3 complex for biophysical imaging studies. In summary, during the previous term of this award we developed robust methods for expression of TCR, and peptide-MHC that now enable us to carry out a multi-disciplinary analysis of a focused set of TCR/pMHC interactions using x-ray crystallography, NMR, peptide libraries, phage display, and electron microscopy (EM).