tRNA editing by deamination: Balancing affinity and specificity

在所有生物体中，tRNAs都是通过一系列转录后处理而成熟的 在它们能够参与蛋白质合成之前发生的事件。其中包括端部修剪以 产生正确的5‘和3’末端，以及相当数量的转录后 化学修饰；这确保了适当的结构和功能。尽管付出了很大的努力 许多修饰还没有在体外重现，这已经使 理解它们的机制即使不是不可能，也是困难的。一个这样的事件需要C 在反密码子上编辑tRNA，这一发现可以追溯到近25年前， 但这是一种没有体外试验的方法。最近，我们在中国建立了第一家 在任何系统中进行C到U编辑的体外试验。我们的研究还表明，在编辑之前 可以发生，编辑的位置也必须甲基化，这两种酶， 脱氨酶和甲基酶的活性相互严格要求。这使我们能够 引入“酶共激活”的新概念，这一概念可能指导生化 目前尚无体外试验的其他修饰的研究。另外， 鉴于布氏锥虫中的tRNA编辑和修改具有独特的特征， 这些研究的成功完成将产生关于 TRNA编辑和修饰的机制和进化，揭示独特的特征 这是布氏锥虫特有的，但无疑会影响其他系统。 好了！

In all organisms, tRNAs are matured by a series of post-transcriptional processing events before they can partake in protein synthesis. These include end trimming to generate the correct 5' and 3' ends, and a substantial number of post-transcriptional chemical modifications; these ensure proper structure and function. Despite much effort many modifications have not been recapitulated in vitro, which have made understanding their mechanism difficult, if not impossible. One such event entails the C to U editing of tRNAs at the anticodon, a discovery that dates back to almost 25 years, but one for which no in vitro assay was available. Recently, we established the first in vitro assay for C to U editing in any system. Our studies also revealed that before editing can take place, the edited position must also be methylated and both enzymes, the deaminase and the methylase, strictly require each other for activity. This allowed us to introduce a new concept of “enzyme co-activation”, one that may guide biochemical studies of other modifications for which no in vitro assay currently exist. Additionally, given that tRNA editing and modification in T. brucei is peppered with unique features, successful completion of these studies will generate important basic information on the mechanism and evolution of tRNA editing and modification, reveal unique features specific to T. brucei but which undoubtedly impact other systems. !