Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128, Mainz, Germany.
Laboratoire de Chimie et Biologie des Métaux, Université Grenoble Alpes, CEA/BIG, CNRS, 17 rue des martyrs, 38000, Grenoble, France.
Angew Chem Int Ed Engl. 2018 Jun 25;57(26):7893-7897. doi: 10.1002/anie.201713188. Epub 2018 Apr 27.
Recently discovered new chemical entities in RNA modifications have involved surprising functional groups that enlarge the chemical space of RNA. Using LC-MS, we found over 100 signals of RNA constituents that contained a ribose moiety in tRNAs from E. coli. Feeding experiments with variegated stable isotope labeled compounds identified 37 compounds that are new structures of RNA modifications. One structure was elucidated by deuterium exchange and high-resolution mass spectrometry. The structure of msms i A (2-methylthiomethylenethio-N6-isopentenyl-adenosine) was confirmed by methione-D3 feeding experiments and by synthesis of the nucleobase. The msms i A contains a thioacetal, shown in vitro to be biosynthetically derived from ms i A by the radical-SAM enzyme MiaB. This enzyme performs thiomethylation, forming ms i A from i A in a first turnover. The new thioacetal is formed by a second turnover. Along with the pool of 36 new modifications, this work describes a new layer of RNA modification chemistry.
最近在 RNA 修饰中的新化学实体的发现涉及到扩大 RNA 化学空间的令人惊讶的功能基团。我们使用 LC-MS 从大肠杆菌的 tRNA 中发现了超过 100 个含有核糖部分的 RNA 成分的信号。用各种稳定同位素标记化合物进行的喂养实验鉴定出 37 种 RNA 修饰的新结构化合物。一种结构通过氘交换和高分辨率质谱法阐明。msms i A（2-甲基硫代亚甲基硫代-N6-异戊烯基-腺嘌呤）的结构通过蛋氨酸-D3 喂养实验和核碱基的合成得到证实。msms i A 含有硫缩醛，体外实验表明它是由 MiaB 酶的自由基-SAM 酶从 ms i A 生物合成而来的。该酶进行硫甲基化，在第一轮反应中从 i A 形成 ms i A。新的硫缩醛是通过第二轮反应形成的。除了 36 种新修饰物的池外，这项工作还描述了 RNA 修饰化学的新层次。
