mRNA Decapping in Yeast

我们工作的长期目标是了解控制真核细胞mrna的分子机制。 稳定性，这是基因调控的关键一步。真核生物信使核糖核酸周转的主要途径之一 起始时有聚(A)尾巴缩短，这会触发去壳，导致5‘-3’外切核解。解封 是这条途径的关键一步，因为它会导致信使核糖核酸的降解，并且是许多 控制输入包括Poly(A)尾巴和调节信使核糖核酸解链速率的特定序列。vt.给出 鉴于这一重要性，我们重点了解了信使核糖核酸解链的机制。在过去，资金 期间，我们澄清了解脱构酶的性质，鉴定了一些蛋白质的作用机制 影响去毛刺率，并提供了强有力的证据表明，去毛发的关键步骤是退出 翻译结合特定mRNP重排的mRNA池。此外，我们还识别了 新的细胞质结构(称为P-小体)，其中信使核糖核酸的分解机制是 集中的和可能发生信使核糖核酸降解的地方。P小体之所以重要，是因为：1)它们暗示 未预料到的信使核糖核酸衰变的区区化，这可能成为信使核糖核酸调控的一个点， 2)在其他真核生物中保守，以及3)很可能是信使核糖核酸生物学中附加事件的位置， 可能包括存储翻译抑制的mRNAs。在这笔赠款中，我们将继续分析 信使核糖核酸分解，重点是了解P小体的组成、性质和功能。这个 具体目标如下： I)测定P小体的成分和超微结构 二)分析P型车身总成 III)分析Dhh1和Pat1蛋白的功能 IV)确定P-小体是否在细胞质mRNA生理的其他方面起作用。

The long-term goal of our work is to understand the molecular mechanisms that control eukaryotic mRNA stability, which is a critical step in gene regulation. One major pathway of mRNA turnover in eukaryotes initiates with poly(A) tail shortening, which triggers decapping, leading to 5' to 3' exonucleolysis. Decapping is a key step in this pathway because it induces degradation of the mRNA, and is the site of numerous control inputs including the poly(A) tail and specific sequences that modulate mRNA decapping rate. Given this importance, we focused on understanding the mechanisms of mRNA decapping. In the past funding period, we clarified the nature of the decapping enzyme, identified the mechanisms by which some proteins affect the rate of decapping, and provided strong evidence that a key step in decapping is exiting the translating pool of mRNAs coupled with a specific mRNP re-arrangement. In addition, we also identified novel cytoplasmic structures (referred to as P-bodies) where the mRNA decapping machinery is concentrated and where mRNA degradation can occur. P-bodies are significant because: 1) they imply unanticipated compartmentalization of mRNA decay, which becomes a possible point of mRNA regulation, 2) are conserved in other eukaryotes and 3) are likely to be sites of additional events in mRNA biology, possibly including storage of translationally repressed mRNAs. In this grant, we will continue our analysis of mRNA decapping with a focus on understanding the composition, properties, and function of P-bodies. The specific aims are as follows: I) Determine the composition and ultrastructure of P-bodies II) Analyze P-body assembly III) Analyze the function of the Dhhl and Pat1 proteins IV) Determine if P-bodies function in other aspects of cytoplasmic mRNA physiology.