STRUCTURAL STUDIES OF RNA ELEMENTS IN PREMRNA SPLICING

描述：计划中的研究的目标是阐明 在前信使核糖核酸剪接反应中起关键作用的三个RNA元件的结构。 关于RNA结构在许多生物中所起的作用，人们知之甚少 它所参与的流程。前-信使核糖核酸剪接是一种极好的 一种研究RNA结构和结构之间关系的系统 功能，因为RNA不仅作为底物参与，而且还参与 结构和催化作用。最常见的前信使核糖核酸形式 剪接是顺式剪接，两个外显子与 内含子的切除。剪接供体或受体区域的突变可以 导致“神秘”剪接部位的使用；一些遗传性疾病 来源于异常剪接产生的改变的基因产物。 反式剪接，涉及短的5‘剪接前导的转移 (SL)序列转换为单独的Pre-mRNA转录本，使用相同的化学方法 并与自剪接共享某些其他结构特征 内含子和顺式剪接。因为许多生物利用了 反式剪接是寄生虫病的罪魁祸首，了解SL RNA 结构为药物设计提供了独特的靶点。 具体目标是确定所涉及的主题的高分辨率结构 在顺式和反式剪接反应中。特别感兴趣的是 遵循内部循环/凸起图案。1)整个第一个的结构 线虫SL1 RNA的茎环将被确定。这根茎 含有一个已知能与特定蛋白质结合的不对称内环。 该项目是对以前结构研究的延伸。2) 酵母剪接体内含子配对形成的隆起区 将对分支位点和U2 SnRNA进行研究。腺嘌呤残留物 这种配对使剪接第一步中的亲核性变得突出。 3)第三个结构目标是由配对形成的凸起区域 剪接体U2和U6的SnRNAs，这是必不可少的两个步骤 前mRNA剪接反应。RNA片段将通过一种组合来研究 多维同核和异核核磁共振技术和 生化方法。从这些研究中获得的信息将提供 关于生物活性RNA形成的结构的新信息 分子及其活动的基础。

DESCRIPTION: The objective of the planned research is to elucidate the structures of three RNA elements critical in pre-mRNA splicing reactions. Little is known about the role RNA structure plays in the many biological processes in which it participates. Pre-mRNA splicing is an excellent system in which to study the relationship between RNA structure and function, because RNA is involved not only as the substrate, but also in structural and in catalytic roles. The most familiar form of pre-mRNA splicing is cis-splicing, the intramolecular joining of two exons with the excision of an intron. Mutations in splice donor or acceptor regions can result in the use of "cryptic" splice sites; a number of genetic diseases stem from altered gene products derived from aberrant splicing. Trans-splicing, which involves the transfer of a short 5' spliced leader (SL) sequence to a separate pre-mRNA transcript, utilizes the same chemistry and shares certain other structural characteristics with the self-splicing introns and with cis-splicing. Since many of the organisms employing trans-splicing are responsible for parasitic disease, knowledge of SL RNA structures presents a unique target for drug design. Specific aims are to determine high resolution structures of motifs involved in cis- and trans-splicing reactions. Particular interest is focused on the following internal loop/bulge motifs. 1) The structure of the entire first stem loop of the SL1 RNA of C. elegans will be determined. The stem contains an asymmetric internal loop known to bind to a specific protein. This project represents an extension of previous structural studies. 2) The bulged region formed by the pairing between the yeast spliceosomal intron branch site and the U2 snRNA will be investigated. The adenine residue bulged out by this pairing is the nucleophile in the first step of splicing. 3) A third structural target is the bulged region formed by the pairing of the spliceosomal U2 and U6 snRNAs, which is essential to both steps in the pre-mRNA splicing reaction. RNA fragments will be studied by a combination of multidimensional homonuclear and heteronuclear NMR techniques and biochemical methods. Information obtained from these studies will provide new information about the structures formed by biologically active RNA molecules and the basis for their activity.