Miniaturized armless tRNAs – function, interaction, modifications

为了在翻译中发挥通用适配元件的作用，tRNAs必须具有结构上的相似性，才能被翻译因子和核糖体等蛋白质生物合成的中心成分识别。因此，它们具有高度保守的三叶草状二级结构，可以折叠成三维的L形状。有趣的是，后生动物线粒体中存在明显结构偏差的tRNA，三叶草形状的单个臂减少或缺失。我们能够在线虫Romanommis culicivorax中检测到tRNA形式减少最多，它只有短的不成对的连接区，而不是D和T臂元件，类似于一个可以折叠成回飞镖状3D形状的发夹。我们想要研究这些连接元件在tRNA结构方面的功能，以及这些极度减少的tRNA与独特的线粒体延长因子mt-EF-Tu的相互作用，从而确定连接元件的进化和延长因子的适应。此外，我们希望确定无臂tRNA中的特定修饰，并研究它们对形成功能性tRNA结构的贡献。这些研究将为线粒体翻译系统的惊人灵活性、其进化以及所涉及的蛋白质因素的适应提供基本的见解。

In order to function as universal adapters in translation, tRNAs must have structural similarities to be recognized by central components of protein biosynthesis such as translation factors and ribosomes. They therefore have a highly conserved cloverleaf-like secondary structure that folds into a three-dimensional L-shape. Interestingly, tRNAs with significant structural deviations exist in the mitochondria of metazoa, with individual arms of the cloverleaf shape being reduced or missing. We were able to detect the most reduced tRNA forms in the nematode Romanomermis culicivorax, which have only short unpaired connector regions instead of D and T arm elements, resembling a hairpin that folds into a boomerang-like 3D shape. We want to investigate the function of these connector elements with regard to the tRNA structure and the interaction of these extremely reduced tRNAs with the unique mitochondrial elongation factor mt-EF-Tu and thereby determine the evolution of the connectors and the adaptation of the elongation factor. Furthermore, we want to identify specific modifications in the armless tRNAs and investigate their contribution to the formation of a functional tRNA structure. These studies will provide fundamental insights into the surprising flexibility of the mitochondrial translation system, its evolution and the adaptation of protein factors involved.