It has been well established that the ribosome can accept various nucleophiles on the Xacyl-tRNA in A site during elongation, where X can be amino, N-alkyl-amino, hydroxy, and thiol groups. However, it remains elusive that the ribosome is able to accept electrophile in P site other than the carboxyl group during elongation. Here we report ribosomal formation of thioamide bond in the mRNA-dependent polypeptide synthesis. In this study, amino(carbothio)acyl-tRNA was prepared by flexizyme and used for the expression of peptides containing a thioamide bond in the nascent peptide chain. We have given strong evidence that the thioamide-peptide was formed but accompanied by the amide counterpart due to rapid carbo(S-to-O) exchange during the preparation of amino(carbothio)acyl-tRNA. We also demonstrated the ribosomal formation of thioamide and N-methyl-thioamide bond in linear as well as macrocyclic peptide scaffolds in the mRNA-dependent manner, showing its potential for applications in peptide-based drug discovery and studying peptide/protein structure and function.

中文翻译：

---

多肽合成中硫代酰胺键的核糖体形成

已经很好地确定，在延伸过程中，核糖体可以在 A 位点的 Xacyl-tRNA 上接受各种亲核试剂，其中 X 可以是氨基、N-烷基-氨基、羟基和硫醇基团。然而，在延伸过程中，核糖体是否能够接受除羧基以外的 P 位点的亲电子试剂，这一点仍然难以捉摸。在这里，我们报告了 mRNA 依赖性多肽合成中硫代酰胺键的核糖体形成。在本研究中，氨基（碳硫基）酰基-tRNA 是通过 flexizyme 制备的，用于表达在新生肽链中含有硫代酰胺键的肽。我们已经提供了强有力的证据表明硫代酰胺肽是形成的，但由于在氨基（硫代）酰基-tRNA 的制备过程中快速的碳（S-to-O）交换而伴随着酰胺对应物。