STRUCTURE DETERMINATION OF AN INTACT BACTERIAL

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 有几类天然存在的催化RNA或核酶。 了解这类生物催化剂如何促进其反应的重要性随着最近50 S核糖体的结构测定而变得显而易见，该结构测定表明所有生物体中的蛋白质合成都发生在RNA活性位点内。 核酶是最有可能成为现代生物催化剂的祖先的分子，了解它们如何促进其反应提供了对酶学功能的重要见解。 该项目的重点是第一类发现的催化RNA的I组自我剪接内含子的结构。 结构信息对于理解和解释这类生物催化剂的生物功能是必要的。 我们正朝着三个目标努力。 1. 该项目的主要目的是确定一个完整的细菌组I自我剪接内含子的高分辨率X射线晶体结构。 如果这一目标得以实现，将开展另外两个项目： 2. 重金属离子和替代内含子抑制剂将被用来从结构上研究金属离子如何有助于I组内含子折叠和催化。 3. 将使用过渡态几何形状的稳定模拟物在结构上探索磷酸转移反应的过渡态。 这些研究将为20多年的生物化学提供结构基础。 它还将提供对RNA催化性质的化学见解，特别是对于RNA金属酶，其中一个例子尚未进行结构分析。 RNA催化是一个特别感兴趣的问题，因为RNA在包括肽键形成和前mRNA剪接在内的几个自然过程中起着关键作用。 这些坐标将提供给科学界进行分析和实验设计。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. There are several classes of naturally occurring catalytic RNAs or ribozymes. The importance of understanding how this class of biocatalysts promotes their reactions became evident with the recent structure determination of the 50S ribosome, which demonstrated that protein synthesis in all living organisms occurs within an RNA active site. Ribozymes are the molecules most likely to be the progenitors of modern biological catalysts and understanding how they promote their reactions provides critical insight into enzymological function. This project focuses on the structure of the group I self-splicing intron, the first class of catalytic RNAs discovered. Structural information is necessary to understand and interpret the biological function of this class of biocatalyst. We are working toward three goals. 1. The primary aim of this project is to determine the high resolution x-ray crystal structure of an intact bacterial group I self-splicing intron. If this aim is achieved, two additional projects will be undertaken: 2. Heavy metal ions and alternative intron inhibitors will be used to structurally investigate how metal ions contribute to group I intron folding and catalysis. 3. The transition state of the phosphotransfer reaction will be structurally explored using stable mimics of the transition state geometry. These studies will provide a structural basis for more than 20 years of biochemistry. It will also provide chemical insights into the nature of RNA catalysis, particularly for an RNA metalloenzyme, an example of which has not yet been structurally analyzed. RNA catalysis is an issue of particular interest given the critical of role of RNA in several natural processes including peptide bond formation and pre-mRNA splicing. The coordinates will be made available to the scientific community for analysis and experimental design.