Definition of Proteasomal Peptide Splicing Rules for High-Efficiency Spliced Peptide Presentation by MHC Class I Molecules
Definition of Proteasomal Peptide Splicing Rules for High-Efficiency Spliced Peptide Presentation by MHC Class I Molecules
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DOI：
10.4049/jimmunol.1402455
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发表时间：
2015-11-01
影响因子：
4.4
通讯作者：
Ovaa, Huib
中科院分区：
文献类型：
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作者：
Berkers, Celia R.;de Jong, Annemieke;Ovaa, Huib
肽剪接（即切除蛋白质的两个远距离部分，然后连接形成新的肽）可以产生独特的 MHC I 类限制性反应。由于这些肽不是基因编码的，并且蛋白酶体剪接背后的规则未知，因此很难预测这些剪接的 Ag。在当前的研究中，使用小型短肽文库来鉴定影响转肽过程效率的氨基酸序列。我们观察到剪接不是随机发生的，无论是在氨基酸序列方面还是通过来自不同来源的肽的随机剪接。相比之下，剪接遵循我们在体外和细胞中推导和验证的不同规则。使用模型肽对肽连接进行定量，并证明在体外连接效率高达 30%，前提是两个连接伙伴都满足连接的最佳结构要求。此外，许多剪接产物可以由单一蛋白质形成。我们的剪接规则将有助于预测和检测新的剪接 Ag，以扩展 MHC I 类 Ag 呈现的肽组。
Peptide splicing, in which two distant parts of a protein are excised and then ligated to form a novel peptide, can generate unique MHC class I-restricted responses. Because these peptides are not genetically encoded and the rules behind proteasomal splicing are unknown, it is difficult to predict these spliced Ags. In the current study, small libraries of short peptides were used to identify amino acid sequences that affect the efficiency of this transpeptidation process. We observed that splicing does not occur at random, neither in terms of the amino acid sequences nor through random splicing of peptides from different sources. In contrast, splicing followed distinct rules that we deduced and validated both in vitro and in cells. Peptide ligation was quantified using a model peptide and demonstrated to occur with up to 30% ligation efficiency in vitro, provided that optimal structural requirements for ligation were met by both ligating partners. In addition, many splicing products could be formed from a single protein. Our splicing rules will facilitate prediction and detection of new spliced Ags to expand the peptidome presented by MHC class I Ags.