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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >PERIODIC VARIATION IN SIDE-CHAIN POLARITIES OF T-CELL ANTIGENIC PEPTIDES CORRELATES WITH THEIR STRUCTURE AND ACTIVITY
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PERIODIC VARIATION IN SIDE-CHAIN POLARITIES OF T-CELL ANTIGENIC PEPTIDES CORRELATES WITH THEIR STRUCTURE AND ACTIVITY

机译：T细胞抗原肽的侧链极性的周期性变化与其结构和活性相关

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摘要

We present an analysis that synthesizes information on the sequence, structure, and motifs of antigenic peptides, which previously appeared to be in conflict, Fourier analysis of T-cell antigenic peptides indicates a periodic variation in amino acid polarities of 3-3.6 residues per period, suggesting an amphipathic alpha-helical structure, However, the diffraction patterns of major histocompatibility complex (MHC) molecules indicate that their ligands are in an extended non-alpha-helical conformation, We present two mutually consistent structural explanations for the source of the alpha-helical periodicity, based on an observation that the side chains of MHC-bound peptides generally partition with hydrophobic (hydrophilic) side chains pointing into (out of) the cleft, First, an analysis of haplotype-dependent peptide motifs indicates that the locations of their defining residues tend to force a period 3-4 variation in hydrophobicity along the peptide sequence, in a manner consistent with the spacing of pockets in the MHC. Second, recent crystallographic determination of the structure of a peptide bound to a class II MHC molecule reveals an extended but regularly twisted peptide with a rotation angle of about 130 degrees, We show that similar structures with rotation angles of 100-130 degrees are energetically acceptable and also span the Length of the MHC cleft. These results provide a sound physical chemical and structural basis for the existence of a haplotype-independent antigenic motif which can be particularly important in limiting the search time for antigenic peptides. [References: 37]
机译：我们提出了一种分析方法，该方法综合了以前似乎存在冲突的抗原性肽的序列，结构和基序上的信息，T细胞抗原性肽的傅立叶分析表明，每个时期3-3.6个残基的氨基酸极性有周期性变化，表明是两亲性的α-螺旋结构，但是，主要组织相容性复合物（MHC）分子的衍射图谱表明，它们的配体处于扩展的非α-螺旋构象中。 -螺旋周期性，基于以下观察结果：结合MHC的肽的侧链通常与指向裂缝（向外）的疏水性（亲水）侧链隔开，首先，单倍型依赖性肽基序的分析表明它们的定义残基倾向于以一致的方式沿着肽序列在疏水性上产生3-4个周期的变化MHC中的口袋间距。其次，最近通过晶体学测定与II类MHC分子结合的肽的结构揭示了延伸但规则扭曲的肽，其旋转角约为130度。我们显示，旋转角为100-130度的相似结构在能量上是可接受的并且还跨越了MHC裂缝的长度。这些结果为不依赖单倍型的抗原基序的存在提供了良好的物理化学和结构基础，这在限制抗原肽的搜索时间中尤其重要。 [参考：37]

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