Yeast eLF2A: A Suppressor of Internal Initiation

酵母 eLF2A：内部启动的抑制剂

基本信息

批准号：
7162095
负责人：
WILLIAM C. MERRICK
金额：
$ 23.86万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-01-01 至 2008-12-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Recent observations indicate that the expression of Ure2p occurs in two manners. The predominant form is via cap-dependent initiation of translation. However, under conditions of "stress", a shorter form of Ure2p is expressed via an IRES that is contained within the coding region of the Ure2 mRNA (corresponding to the Nterminal region of the protein). An apparently unrelated finding has been the identification of the yeast homolog to the human eIF2A gene which is non-essential for yeast growth. However, when the expression of the smaller form of the Ure2p protein (via a reporter system fused to lacZ) was monitored in the eIF2A deletion strain, expression oflacZ was increased 6 to 10-fold. In the simplest of terms, eIF2A would appear to be a suppressor of the IRES function found in the Ure2 mRNA. We propose the following 4 questions to more fully evaluate these findings: 1. What are the cis-acting sequences in Ure2p mRNA that are required to allow internal initiation? 2. What other yeast mRNAs are initiated via internal initiation? 3. How is control of internal initiation regulated, through covalent modification or protein content? 4. What portion of eIF2A is required to suppress internal initiation and with what proteins does it interact in this process? Given the general observation that in many systems, "stress" leads to cap-independent initiation (i.e. internal initiation), we feel that we have discovered an ideal model system in which to study the switch from capdependent to cap-independent translation. It is anticipated that the mechanism defined in the yeast system will have broad applicability and will likely provide insights into mammalian systems where there have been numerous reports on the utilization of cap-independent translation (heat shock, apoptosis, viral infection, etc.)

描述（由申请人提供）：最近的观察结果表明，Ure2p的表达以两种方式出现。主要形式是通过帽依赖性的翻译开始。然而，在“应力”条件下，URE2P的较短形式通过包含在URE2 mRNA的编码区域内的IRE表示（对应于蛋白质的N端区域）。一个显然无关的发现是对人EIF2A基因的酵母同源物的鉴定，这对于酵母生长而言是非必需的。但是，当在EIF2A缺失菌株中监测URE2P蛋白的较小形式的表达（通过融合与LACZ的报告）的表达时，乳杆菌的表达增加了6至10倍。用最简单的术语来说，EIF2A似乎是URE2 mRNA中发现的IRES函数的抑制剂。我们提出以下4个问题，以更全面地评估这些发现： 1。允许内部启动所需的URE2P mRNA中的顺式作用序列是什么？ 2。通过内部启动启动了其他哪些酵母mRNA？ 3。如何通过共价修饰或蛋白质含量来调节内部起始的控制？ 4。抑制内部启动需要哪一部分EIF2A，并且在此过程中它相互作用是什么？鉴于在许多系统中的一般观察结果，“应力”会导致独立于帽帽的启动（即内部启动），我们认为我们已经发现了一个理想的模型系统，可以在其中研究从capdepdentent到cap独立的翻译转换。预计酵母系统中定义的机制将具有广泛的适用性，并且可能会提供有关哺乳动物系统的见解，在这些系统中，有许多有关帽帽非依赖性翻译的报道（热休克，凋亡，病毒感染等）。