Dimethylation of amino acids consists of an interesting and puzzling series of events that could be achieved, during nonribosomal peptide biosynthesis, either by a single adenylation (A) domain interrupted by a methyltransferase (M) domain or by the sequential action of two of such independent enzymes. Herein, to establish the method by which Nature N,S-dimethylates l-Cys, we studied its formation during thiochondrilline A biosynthesis by evaluating TioS(A_3aM_3SA_3bT₃) and TioN(A_aM_NA_b). This study not only led to identification of the exact pathway followed in Nature by these two enzymes for N,S-dimethylation of l-Cys, but also revealed that a single interrupted A domain can N,N-dimethylate amino acids, a novel phenomenon in the nonribosomal peptide field. These findings offer important and useful insights for the development and engineering of novel interrupted A domain enzymes to serve, in the future, as tools for combinatorial biosynthesis.

中文翻译：

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破解自然界复杂的N，S-二甲基化半胱氨酸的方式：两个双功能腺苷酸化域的顺序作用

氨基酸的二甲基化包括一系列有趣且令人费解的事件，这些事件可以在非核糖体肽生物合成过程中通过单个甲基化（M）结构域中断的单个腺苷酸化（A）结构域，或通过两个此类独立分子的顺序作用来实现酶。在本文中，为了建立自然N，S-二甲基化L -Cys的方法，我们通过评估TioS（A _3a M _3S A _3b T ₃）和TioN（A _a M _N A _b）。这项研究不仅确定了自然界中这两种酶对L -Cys进行N，S-二甲基化所遵循的确切途径，而且还揭示了一个单独的中断A结构域可以使N，N-二甲基化氨基酸，这是一种新现象在非核糖体肽领域。这些发现为新型中断的A结构域酶的开发和工程设计提供了重要而有用的见解，将来可作为组合生物合成的工具。