Peptide linkage to the α-subunit of MHCII creates a stably inverted antigen presentation complex.
Peptide linkage to the α-subunit of MHCII creates a stably inverted antigen presentation complex.
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与 MHCII α 亚基的肽连接创建稳定的反向抗原呈递复合物
DOI：
10.1016/j.jmb.2012.07.008
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发表时间：
2012
影响因子：
5.6
通讯作者：
Freund
中科院分区：
文献类型：
--
作者：
Schlundt;Günther;Sticht;Wieczorek;Heinemann;Freund
主要组织相容性复合体（MHCII）的II类蛋白通常呈现外源性抗原肽，以同源CD4-T淋巴细胞的T细胞受体。肽- mhcii复合物（pMHCII）的确切构象可以根据结合肽的长度、定位和取向而变化。我们最近发现自肽CLIP （ii类相关不变链衍生肽）与人类MHCII HLA- dr1 （HLA，人类白细胞抗原）采用动态双向结合模式。我们认为，在自身免疫的背景下，反向结合的肽可以激活特异性T细胞克隆。作为证明这一假设的第一步，必须构建局限于典型或倒肽取向的pMHC复合物。在这里，我们展示了CLIP和其他两种抗原肽与HLA-DR1 α-链的遗传编码连锁导致与反向结合配体的稳定配合物。二维核磁共振和生物物理分析表明，clip结合的pMHCinv复合物（pMHCinv，倒置mhcii肽复合物）具有很高的热力学稳定性，但仍然允许与高亲和力的病毒抗原进行交换。通过对相应的β-链融合的典型HLA-DR1/CLIP复合体的比较数据的补充，我们进一步表明，CLIP的连锁导致的结合模式与相应的非连锁结构完全相同。我们建议我们的方法构成了创建pmhcincomplexes的一般策略。为了研究同分异构体pmhc引起的自身免疫现象，需要这种工程技术来制造定向特异性抗体和培养T细胞。
Class II proteins of the major histocompatibility complex (MHCII) typically present exogenous antigenic peptides to cognate T cell receptors of CD4-T lymphocytes. The exact conformation of peptide–MHCII complexes (pMHCII) can vary depending on the length, register and orientation of the bound peptide. We have recently found the self-peptide CLIP (class‐II-associated invariant chain‐derived peptide) to adopt a dynamic bidirectional binding mode with regard to the human MHCII HLA-DR1 (HLA, human leukocyte antigen). We suggested that inversely bound peptides could activate specific T cell clones in the context of autoimmunity. As a first step to prove this hypothesis, pMHC complexes restricted to either the canonical or the inverted peptide orientation have to be constructed. Here, we show that genetically encoded linkage of CLIP and two other antigenic peptides to the HLA-DR1 α-chain results in stable complexes with inversely bound ligands. Two‐dimensional NMR and biophysical analyses indicate that the CLIP-bound pMHCinvcomplex (pMHCinv, inverted MHCII–peptide complex) displays high thermodynamic stability but still allows for the exchange against higher‐affinity viral antigen. Complemented by comparable data on a corresponding β-chain-fused canonical HLA-DR1/CLIP complex, we further show that linkage of CLIP leads to a binding mode exactly the same as that of the corresponding unlinked constructs. We suggest that our approach constitutes a general strategy to create pMHCinvcomplexes. Such engineering is needed to create orientation-specific antibodies and raise T cells to study phenomena of autoimmunity caused by isomeric pMHCs.