Analysis of mutant HLA-A2 molecules. Differential effects on peptide binding and CTL recognition.
Analysis of mutant HLA-A2 molecules. Differential effects on peptide binding and CTL recognition.
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DOI：
10.4049/jimmunol.152.3.1213
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发表时间：
1994-02
影响因子：
4.4
通讯作者：
L. Tussey;M. Matsui;S. Rowland-Jones;R. Warburton;J. Frelinger;A. McMichael
中科院分区：
文献类型：
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作者：
L. Tussey;M. Matsui;S. Rowland-Jones;R. Warburton;J. Frelinger;A. McMichael
以前的研究已经确定了几个残基内衬的HLA-A2.1分子的沟，是关键的银呈递。然而，尚不清楚这些残基对于肽表位本身的结合或对于确定结合肽的适当构象是否是关键的。为了区分这些可能性，在这些残基中的8个的突变已经被测试了它们对分子结合和呈递两个已知肽表位的能力的影响-一个来自A型流感病毒基质蛋白，另一个来自HIV pol。只有一个例外，突变被发现类似地影响两个肽的结合。大多数突变导致对结合的中等有害影响，其中B口袋突变体F9 Y对两种肽的结合具有最显著的负面影响。两个突变显著增强了两种肽的结合，并且用取代Y 99 H观察到对结合的肽特异性效应，其增强了基质肽的结合，但减少了pol肽的结合。与对结合的影响相反，对于两种肽，突变对呈递的影响差异很大。最显著的差异见于两种α 2 α螺旋突变体，其完全被pol肽特异性CTL识别，但不被基质肽特异性CTL识别，即使这两种肽的结合水平显著降低。这些结果表明，一些相互作用，虽然不是关键的结合本身，是关键的功能结合和这些相互作用的重要性不同的肽表位。
Previous studies have identified several residues lining the groove of the HLA-A2.1 molecule that are critical for Ag presentation. However, it is not clear whether these residues are critical for binding of the peptide epitope per se or for determining the appropriate conformation of bound peptide. To distinguish between these possibilities, mutations at eight of these residues have been tested for their effects on the ability of the molecule to bind and present two known peptide epitopes--one derived from the influenza A matrix protein, the other from HIV pol. With only one exception, the mutations were found to affect the binding of the two peptides similarly. Most of the mutations resulted in intermediate deleterious effects on binding, with the B pocket mutant F9Y having the most dramatic negative effect on binding for both peptides. Two of the mutations significantly enhanced binding of both peptides and a peptide-specific effect on binding was seen with the substitution, Y99H, which enhanced binding of the matrix peptide yet diminished binding of the pol peptide. In contrast to the effects on binding, the effects of the mutations on presentation differed considerably for the two peptides. The most striking difference was seen with two alpha 2 alpha helix mutants that are fully recognized by pol peptide-specific CTL but not recognized by matrix peptide-specific CTL even though levels of binding were comparably diminished for the two peptides. These results suggest that some interactions, although not critical for binding per se, are critical for functional binding and the importance of these interactions differs among peptide epitopes.