Leighton J, Sette A, Sidney J, Appella E, Ehrhardt C, Fuchs S, Adorini L
Preclinical Research, Sandoz Pharma Ltd., Basel, Switzerland.
J Immunol. 1991 Jul 1;147(1):198-204.
We have analyzed the interaction of the hen egg-white lysozyme (HEL) peptide 107-116 with the MHC class II molecule I-Ek, using truncated and single residue substitution analogues to measure activation of I-Ek-restricted, 107-116-specific T cell hybridomas and competition for Ag presentation by I-Ek molecules. These results have been compared with previous findings on the interaction of the same peptide with the I-Ed molecule. Stimulation of T cell hybridomas by truncated peptides defines the sequence 108-116 as the minimum epitope necessary for activation of both I-Ek- and I-Ed-restricted T cell hybridomas. Substitution analysis pinpoints three residues (V109, A110, and K116) in the sequence 108-116 as being critical for binding to I-Ek molecules and demonstrates the involvement of most other residues in recognition by T cells. Results previously obtained for binding of HEL 107-116 to I-Ed molecules indicated that peptide residues R112, R114, and K116 were critical for interaction with I-Ed. Comparison of these results indicates a difference in the likely MHC contact residues between the HEL sequence 108-116 and I-Ed or I-Ek molecules, suggesting that the same HEL peptide assumes a different conformation in the binding site of these two MHC molecules. This in turn affects residues interacting with the specific T cell receptor. According to the hypothetical tridimensional structure predicted for class II molecules, the difference in MHC contact residues observed within the sequence 108-116 can be related to polymorphic amino acids in the binding site of I-Ek and I-Ed molecules. A search through published binding data for a common pattern in this and other I-Ek-binding peptides has permitted us to derive a possible motif for predicting peptide binding to I-Ek molecules. This putative motif was tested by determining binding to I-Ek of an unbiased panel of about 150 synthetic peptides. Binding data indeed demonstrate the presence of this motif in the majority of good binders to I-Ek molecules.
我们使用截短的和单残基取代类似物，分析了鸡卵清溶菌酶（HEL）肽107 - 116与MHC II类分子I-Ek的相互作用，以测量I-Ek限制性、107 - 116特异性T细胞杂交瘤的激活情况以及I-Ek分子对抗原呈递的竞争。这些结果已与先前关于同一肽与I-Ed分子相互作用的研究结果进行了比较。截短肽对T细胞杂交瘤的刺激将序列108 - 116定义为激活I-Ek和I-Ed限制性T细胞杂交瘤所需的最小表位。取代分析确定了序列108 - 116中的三个残基（V109、A110和K116）对于与I-Ek分子结合至关重要，并证明了大多数其他残基参与T细胞的识别。先前获得的关于HEL 107 - 116与I-Ed分子结合的结果表明，肽残基R112、R114和K116对于与I-Ed的相互作用至关重要。这些结果的比较表明，HEL序列108 - 116与I-Ed或I-Ek分子之间可能的MHC接触残基存在差异，这表明相同的HEL肽在这两种MHC分子的结合位点中呈现出不同的构象。这进而影响与特定T细胞受体相互作用的残基。根据预测的II类分子三维结构，在序列108 - 116中观察到的MHC接触残基差异可能与I-Ek和I-Ed分子结合位点中的多态性氨基酸有关。通过搜索已发表的结合数据以寻找该序列和其他I-Ek结合肽中的共同模式，使我们能够推导预测肽与I-Ek分子结合的可能基序。通过测定约150种合成肽的无偏集与I-Ek的结合情况，对该假定基序进行了测试。结合数据确实证明了该基序在大多数与I-Ek分子结合良好的肽中存在。
