Mechanisms of 3' Splice Site Selection in S. cerevisiae

酿酒酵母 3 剪接位点选择机制

• 批准号: 6833484
• 负责人: David Scott McPheeters
• 金额: $ 22.49万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6833484
• 关键词: RNA binding protein; RNA splicing; SDS polyacrylamide gel electrophoresis; Saccharomyces cerevisiae; active sites; adenosine triphosphate; affinity chromatography; binding sites; dinucleotide; enzyme mechanism; helicase; hydrolysis; immunoprecipitation; intermolecular interaction; introns; messenger RNA; phosphorus; point mutation; precursor mRNA; radionuclides; small nuclear RNA; small nuclear ribonucleoproteins; spliceosomes; yeasts

The removal of introns from nuclear pre-mRNAs requires the assembly of a large macromolecular machine termed the spliceosome. In humans, it has been estimated that the spliceosome must be able to recognize and precisely excise as many as 106 different introns of varying lengths and sequences. The precise identification of intron boundaries and their excision by the spliceosome is accomplished through the highly ordered and dynamic assembly of five small nuclear ribonucleoprotein particles and more than sixty proteins onto a pre-mRNA. During many of the assembly steps, RNA helices are formed and/or broken in reactions requiring enzymes termed ATP- dependent RNA helicases. Intriguingly, genetic analyses in yeast have indicated that ATP-hydrolysis by RNA helicases can function in proofreading steps that insure the fidelity of splice site choice. Prp16p is an RNA helicase that catalyzes a conformational change in the spliceosome acts to insure the fidelity of intron branch site selection. Recent results have suggested that ATP hydrolysis by Prp16 may lead to the creation of a binding site for the 3' splice site. The first major goal of the proposed research is to identify the RNA substrates for the RNA helicase activity of Prp16p within the spliceosome, and to characterize the rearrangements of RNA/RNA and RNA/protein interactions that occur as a consequence of ATP hydrolysis by Prp16p. The nature of the interactions that may serve to connect ATP hydrolysis by Prp16p to the fidelity of branch site recognition will also be determined. Second, we will determine if ATP hydrolysis by Prp16p leads to changes in the interactions of U2/U6 helix I, a helix that has a critical function in the second step. Third, because the rearrangements facilitated by Prp16p may culminate in the formation of a binding site for the 3' splice site, we will determine if changes in the interactions involving the 3' splice site are directly tied to ATP hydrolysis by Prp16p. A detailed picture of the role of a specific member of the RNA helicase family in splicing should help elucidate the principles by which they function. Because these enzymes have important roles in all aspects of cellular RNA metabolism, the results of these studies will be relevant to the study of their functions in other biological contexts.

从核前MRNA中去除内含子需要组装的大型大分子机器称为剪接体。 在人类中，据估计，剪接体必须能够识别并精确地切除多达106个不同长度和序列的不同内含子。通过高度有序和动态组装的五个小核核糖核蛋白颗粒和超过60种蛋白质的夹层组装来完成内含子边界的精确鉴定及其通过剪接体切除。 在许多组装步骤中，在需要称为ATP依赖性RNA旋转酶的酶的反应中形成RNA螺旋和/或破裂。 有趣的是，酵母中的遗传分析表明，RNA解旋酶通过RNA解旋酶进行的ATP-Hydrolssis可以在校对步骤中起作用，从而确保剪接位点选择的忠诚度。 PRP16P是一种RNA解旋酶，可催化剪接体的构象变化可确保内含子分支位点选择的保真度。 最近的结果表明，PRP16的ATP水解可能导致创建3'剪接位点的结合位点。拟议的研究的第一个主要目标是鉴定剪接体内PRP16P的RNA解旋酶活性的RNA底物，并表征RNA/RNA和RNA/RNA/蛋白质相互作用的重排，这是由于PRP16P通过ATP水解而发生的。 还将确定可以通过PRP16P将ATP水解与分支位点识别的保真度联系起来的相互作用的性质。 其次，我们将确定PRP16P的ATP水解是否会导致U2/U6螺旋I的相互作用变化，U2/U6螺旋I（在第二步中具有关键功能的螺旋螺旋体）是否会发生变化。 第三，由于PRP16P促进的重排可能在3'剪接位点的结合位点形成中最终导致，因此我们将确定涉及3'剪接位点的相互作用的变化是否直接与PRP16P的ATP水解息息相关。 RNA解旋酶家族特定成员在剪接中的作用的详细图片应有助于阐明其发挥作用的原理。 由于这些酶在细胞RNA代谢的各个方面具有重要作用，因此这些研究的结果将与其他生物学背景下的功能有关。