Binding of peptides lacking consensus anchor residue alters H-2Ld serologic recognition.
Binding of peptides lacking consensus anchor residue alters H-2Ld serologic recognition.
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DOI：
10.4049/jimmunol.151.10.5387
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发表时间：
1993-11
影响因子：
4.4
通讯作者：
J. Solheim;B. Carreno;J. D. Smith;J. Gorka;N. Myers;Zilong Wen;J. Martinko;David R. Lee;T. Hansen
中科院分区：
文献类型：
--
作者：
J. Solheim;B. Carreno;J. D. Smith;J. Gorka;N. Myers;Zilong Wen;J. Martinko;David R. Lee;T. Hansen
CTL识别靶细胞表面的I类MHC/肽复合物。晶体学和血清学数据表明，肽配体可以影响I类分子的构象，从而影响T细胞的识别。具有不同序列基序的肽的结合如何影响I类分子内不同区域的构象仍然未知。为了解决这个问题，研究人员对小鼠I类分子H-2Ld的一系列位点定向突变进行了研究。这些突变体是通过体外诱变产生的，并用于绘制由一组ld反应性单抗识别的血清学表位。然后检测了六种不同配体对这些单抗血清学识别的影响。在测试的12个单抗中，只有B22/249被发现受到结合肽的显著影响。B22/249与其中两种配体孵育后，在细胞表面和Ld免疫沉淀物中观察到多肽识别。导致B22/249对Ld/肽的次优识别的两种肽在2位缺乏脯氨酸，而脯氨酸存在于其他四种肽中，并且先前被定义为Ld配体的锚定残基。单抗B22/249检测到的Ld表位包括α 1结构域螺旋上的63 ~ 70个残基。其中两个残基在口袋B中，计算机模型预测它与ld结合肽的第二个残基接触。因此，这些数据表明，针对I类分子的mAb可以区分具有不同基序的肽，可能反映了I类分子中肽依赖的构象变化。
CTL recognize class I MHC/peptide complexes on the surface of target cells. Crystallographic and serologic data have indicated that peptide ligands can influence the conformation of class I molecules and hence T cell recognition. How the binding of peptides with disparate sequence motifs affects the conformation of distinct regions within a class I molecule remains unknown. A series of site-directed mutants of the murine class I molecule H-2Ld was studied to address this question. These mutants were generated by in vitro mutagenesis and used to map the serologic epitopes recognized by a panel of Ld-reactive mAb. The influence of six different ligands on serologic recognition by these mAb was then examined. Of 12 mAb tested, only one, B22/249, was found to be significantly influenced by the bound peptide. Peptide discrimination by B22/249 was observed at the cell surface and in immunoprecipitates of Ld after incubation with two of the six ligands. The two peptides that caused suboptimal B22/249 recognition of Ld/peptide lack a proline at position 2, which is present in the other four peptides and has previously been defined as an anchor residue for Ld ligands. The epitope on Ld detected by mAb B22/249 includes residues 63 to 70 on the alpha 1 domain helix. Two of these residues are in pocket B, which computer modeling predicts to be in contact with the second residue of Ld-binding peptides. Therefore, these data imply that a mAb to a class I molecule can distinguish peptides with different motifs, possibly reflecting peptide-dependent conformational changes in the class I molecule.