W.M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland, USA; Department of Histology and Embryology, Hengyang Medical School, University of South China, Hengyang, Hunan, China; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA.
W.M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland, USA; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA.
J Biol Chem. 2022 Mar;298(3):101684. doi: 10.1016/j.jbc.2022.101684. Epub 2022 Feb 3.
Adoptive cell therapy with tumor-specific T cells can mediate durable cancer regression. The prime target of tumor-specific T cells are neoantigens arising from mutations in self-proteins during malignant transformation. To understand T cell recognition of cancer neoantigens at the atomic level, we studied oligoclonal T cell receptors (TCRs) that recognize a neoepitope arising from a driver mutation in the p53 oncogene (p53R175H) presented by the major histocompatibility complex class I molecule HLA-A2. We previously reported the structures of three p53R175H-specific TCRs (38-10, 12-6, and 1a2) bound to p53R175H and HLA-A2. The structures showed that these TCRs discriminate between WT and mutant p53 by forming extensive interactions with the R175H mutation. Here, we report the structure of a fourth p53R175H-specific TCR (6-11) in complex with p53R175H and HLA-A2. In contrast to 38-10, 12-6, and 1a2, TCR 6-11 makes no direct contacts with the R175H mutation, yet is still able to distinguish mutant from WT p53. Structure-based in silico mutagenesis revealed that the 60-fold loss in 6-11 binding affinity for WT p53 compared to p53R175H is mainly due to the higher energetic cost of desolvating R175 in the WT p53 peptide during complex formation than H175 in the mutant. This indirect strategy for preferential neoantigen recognition by 6-11 is fundamentally different from the direct strategies employed by other TCRs and highlights the multiplicity of solutions to recognizing p53R175H with sufficient selectivity to mediate T cell killing of tumor but not normal cells.
采用肿瘤特异性 T 细胞的过继细胞疗法可以介导持久的癌症消退。肿瘤特异性 T 细胞的主要靶标是恶性转化过程中自我蛋白突变产生的新抗原。为了在原子水平上理解 T 细胞对癌症新抗原的识别,我们研究了识别由 p53 癌基因中的驱动突变(p53R175H)产生的新表位的寡克隆 T 细胞受体(TCR),该表位由主要组织相容性复合物 I 类分子 HLA-A2 呈递。我们之前报道了三种与 p53R175H 特异性 TCR(38-10、12-6 和 1a2)结合的 p53R175H 特异性 TCR 的结构,这些 TCR 与 p53R175H 和 HLA-A2 结合。这些结构表明,这些 TCR 通过与 R175H 突变形成广泛的相互作用来区分 WT 和突变型 p53。在这里,我们报告了第四个 p53R175H 特异性 TCR(6-11)与 p53R175H 和 HLA-A2 复合物的结构。与 38-10、12-6 和 1a2 不同,TCR 6-11 与 R175H 突变没有直接接触,但仍能够区分突变型和 WT p53。基于结构的计算机诱变显示,与 p53R175H 相比,6-11 对 WT p53 的结合亲和力降低了 60 倍,主要是由于在复合物形成过程中,WT p53 肽中 R175 的去溶剂化能量成本高于突变体中的 H175。6-11 通过这种间接策略优先识别新抗原与其他 TCR 采用的直接策略有根本的不同,这突出了识别 p53R175H 的多种解决方案,具有足够的选择性来介导 T 细胞杀伤肿瘤而不杀伤正常细胞。