Determination of an Intact Bacterial Group I Intron Structure by X-ray Crystallography

本项目的目标是获得完整的细菌I组自我剪接内含子的高分辨率X射线晶体结构。晶体学目标是紫色细菌Azoarcus的内含子。该内含子位于前tRNA Ile的反密码子环中。这是迄今为止发现的最小的I组内含子。然而，它保留了I组核酶共有的保守二级和三级结构元件，并且非常稳定。该项目的第一个目标是获得保留其所有组件的复合物的结构，包括末端G，5'和3'外显子和底物螺旋。这些结构信息将被用来探索金属离子如何促进RNA催化，并研究这种核酶促进的磷酰基转移反应的化学过渡态。核酶，如这个内含子，是最有可能成为现代生物催化剂的祖先的分子。了解它们是如何促进反应的，将为了解酶的功能提供有价值的见解。这项研究将为核酸化学和结构生物学的接口提供培训机会。

The goal of this project is to obtain the high resolution X-ray crystal structure of an intact bacterial group I self-splicing intron. The crystallographic target is the intron from the purple bacterium Azoarcus. This intron is located in the anticodon loop of the pre-tRNA Ile. It is the smallest group I intron identified to date. Yet, it retains the conserved secondary and tertiary structural elements common to group I ribozymes and is exceptionally stable. The first goal of the project is to obtain the structure of a complex that retains all of its components, including the terminal G, the 5' and 3' exons and the substrate helix. This structural information will be used to explore how metal ions contribute to RNA catalysis and to investigate the chemical transition state of the phosphoryl transfer reactions promoted by this ribozyme. Ribozymes, such as this intron, are the molecules most likely to be the progenitors of modern biological catalysts. Understanding how they promote their reactions will provide valuable insight into enzymological function. The research will provide opportunities for training at the interface of nucleic acid chemistry and structural biology.