tRNA editing by deamination: Balancing affinity and specificity

在所有生物体中，tRNA通过一系列转录后加工而成熟 在它们参与蛋白质合成之前发生的事件。这些包括末端修剪， 产生正确的5'和3'末端，以及大量的转录后转录产物。 化学修饰;这些确保适当的结构和功能。尽管付出了很多努力 许多修饰尚未在体外重现， 理解它们的机制很困难，如果不是不可能的话。一个这样的事件需要C 到反密码子上的tRNA的U编辑，这一发现可以追溯到近25年前， 但是没有可用的体外测定。最近，我们建立了第一个在 在任何系统中进行C至U编辑的体外测定。我们的研究还显示，在编辑之前， 可以发生，编辑的位置也必须被甲基化，并且两种酶， 脱氨酶和甲基化酶，严格要求彼此的活性。这使我们能够 介绍了一个新概念“酶共激活”，一个可以指导生物化学 目前没有体外试验的其他修饰研究。此外，本发明还 鉴于T.布鲁塞有很多独特的地方， 这些研究的成功完成将产生重要的基本信息， tRNA编辑和修饰的机制和进化，揭示其独特的功能 对T.但这无疑会影响其他系统。 !

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. !