POLY-A FUNCTION & METABOLISM IN SACCHAROMYCES CEREVISIAE

基因是如何通过改变其代谢来进行差异调节的 成熟mRNA是分子生物学中的关键问题。 潜在的点 调节包括核质mRNA转运，mRNA稳定性， mRNA翻译效率。 mRNA的poly（A）尾被认为是 重要的每一个这些过程，但没有明确的了解聚 (A)tail函数存在。 这项工作的长期目标是 分析poly（A）在mRNA代谢中的作用，并了解其如何 修饰在它或蛋白质结合到它，聚（A）-结合 蛋白质，可以影响这种新陈代谢。 有了这样的理解， mRNa代谢中poly（A）依赖性步骤的改变， 可以研究细胞感染或转化。 这项工作的最初目标是描述酵母中的基因 酿酒酵母，其影响poly（A）的合成、包装和降解。 这些基因包括编码多聚腺苷酸聚合酶的基因、多聚腺苷酸结合酶的基因和编码多聚腺苷酸结合酶的基因。 蛋白质，和七个基因（spb 1-spb 7），当突变时，允许细胞 没有必需的多聚腺苷酸结合蛋白也能存活。 其中之一，SPB 2， 编码核糖体蛋白L46，另一个，SPB 4，编码一种蛋白 其与真核起始因子4a高度同源， 可能是RNA解旋酶 这些基因的突变对 体内mRNA转运、poly（A）和mRNA稳定性以及mRNA翻译将 接受检查。 一种体外聚（A）降解试验， 复制这些突变的体内效应。 这 该测定将检测poly（A）尾和 mRNA的剩余部分，这将是一个研究 信使核糖核蛋白结构及其对mRNA稳定性的影响。

How genes are differentially regulated by altering the metabolism of their mature mRNA is a key question in molecular biology. Potential points of regulation include nuclear-cytoplasmic mRNA transport, mRNA stability, and mRNA translational efficiency. The poly(A) tail of mRNA is considered important for each of these processes, yet no clear understanding of poly (A) tail function exists. The long term objective of this work is to analyze the role(s) of poly(A) in mRNA metabolism and to understand how modifications in it or the protein bound to it, the poly(A)-binding protein, can affect this metabolism. With this understanding, potential alterations of poly(A)-dependent steps in mRNa metabolism resulting from cellular infection or transformation can be studied. The initial objective of the work is to characterize genes in Saccharomyces cerevisiae which affect poly(A) synthesis, packaging, and degradation. These include genes encoding a poly(A)-polymerase, the poly(A)-binding protein, and seven genes (spbl-spb7) which when mutated allow the cells to live without the essential poly(A)-binding protein. One of these, SPB2, encodes the ribosomal protein L46, and another, SPB4, encodes a protein which is highly homologous to eucaryotic initiation factor 4a and is probably an RNA-helicase. The effects of mutations in these genes on in vivo mRNA transport, poly(A) and mRNA stability, and mRNA translation will be examined. An in vitro poly(A)-degradation assay that faithfully reproduces the in vivo effects of these mutations will be developed. This assay will detect the functional interactions between the poly(A) tail and the remainder of the mRNA, and it will be a model system for studying messenger ribonucleoprotein structure and its affects on mRNA stability.