Novel Control of Translation Initiation by Barley Yellow Dwarf Virus

;​R o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o:;= ?@ A B C F微软Word 6.0文档6;​大多数病毒都有RNA基因组，因此翻译而不是转录是基因表达的重要调控步骤。然而，对翻译控制的研究一直被忽视，特别是在植物中。大麦黄矮病毒（Barley yellow dwarf virus， BYDV） （PAV血清型）独特丰富的翻译机制，使其成为研究翻译控制基因表达的有价值的模型。通过提供翻译细胞机制的“例外”，BYDV等病毒应该揭示翻译是如何工作的。这里研究的三种现象特别重要，原因如下。(i)在病毒RNA 5′端超过4.5 kb的地方，一个序列的位置无法根据目前对翻译起始的理解来解释。（二）对两个起始密码子起始控制的新模型进行试验，该模型可能具有广泛的应用前景。（iii）多种病毒使用我们发现的保守序列基序两侧的停止密码子的读通。对于这类读出信号的控制，我们一无所知。此外，BYDV是世界上最具经济价值的小谷物病毒。了解其基因表达是如何被控制的，可能会导致控制这种病毒以及具有这些新的翻译机制的医学上重要的病毒的方法。遗传密码被破译和蛋白质被制造的过程叫做翻译。细胞机制读取作为信使RNA （mRNA，类似于DNA）中核苷酸序列编码的遗传信息，以合成特定的蛋白质分子。在所有细胞mrna的翻译起始位点都需要一种叫做帽的化学修饰。一些病毒mrna缺乏帽，但被宿主的机器非常有效地翻译。大麦黄矮病毒（BYDV）是世界上最重要的谷类病毒，其基因组是一个RNA分子。它有一个序列，在功能上替代帽，位于从翻译开始的数千个核苷酸（几个基因长度）上。目标：(i)通过将特异性改变形式的BYDV RNA引入细胞自由翻译系统或植物细胞，确定该序列的功能，并监测蛋白质合成；（ii）确定序列的结构及其与细胞分子的相互作用；（iii）将该序列连接到所需的非病毒基因上，以增强其在植物中的翻译。这项工作将帮助我们理解遗传密码是如何被解码的；通过选择性破坏病毒蛋白合成抑制病毒感染的设计方法；改进用于基因工程的分子工具。*** @ @ Oh +' 0 $ H l D H R:\WWUSER\TEMPLATE\NORMAL。DOT玛西娅·斯坦伯格玛西娅·斯坦伯格@ @ @“我是我的妈妈，我是我的妈妈，我是我的妈妈。微软Word 6.0 4e3ejjjjjjjjj7 1h T 4 7 j 7 j j j j j ~ j j j j j j j 1[9420806]米勒大多数病毒都有RNA基因组，因此可以翻译

; R o o t E n t r y F C o m p O b j b W o r d D o c u m e n t O b j e c t P o o l m m : ; = ? @ A B C F Microsoft Word 6.0 Document MSWordDoc Word.Document.6 ; 9420806 Miller Most viruses have RNA genomes, thus translation, rather than transcription serves as an important regulatory step in gene expression. Yet the study of translational control has been neglected, especially in plants. Barley yellow dwarf virus (BYDV) (PAV serotype) is uniquely rich in novel translation mechanisms, making it a valuable model for the study of translational control of gene expression By providing "exceptions" to the cellular mechanisms of translation, viruses such as BYDV should shed light on how translation works. The three phenomena investigated here are particularly significant for the following reasons. (i) The location of a sequence, that confers cap independent translation over 4.5 kb from the 5' end of the viral RNA, defies explanation based on current understanding of translation initiation. (ii) A new model for control of initiation at two start codons, which may have wide application, will be tested. (iii) A wide variety of viruses employ readthrough of stop codons flanked by conserved sequence motifs that we identified. Nothiny is known about control of this cla ss of readthrough signals. In addition, BYDV is the most economically important virus of small grains worldwide. Understanding how its gene expression is controlled may lead to methods for controlling this virus as well as medically important viruses which share these novel translation mechanisms. %%% The process in which the genetic code is decoded and proteins are made is called translation. Cellular machinery reads genetic information encoded as a sequence of nucleotides in messenger RNA (mRNA, similar to DNA), to synthesize a specific protein molecule. A chemical modification called a cap is required at the start site of translation on all cellular mRNAs. Some viral mRNAs lack the cap, yet are translated very effidently by the host's machinery. The genome of barley yellow dwarf virus (BYDV), the most important virus of cereals worldwide, is an RNA molecule. It has a sequence, that functionally substitutes for a cap, located thousands of nucleotides (several gene lengths) from the translation start. Goals: (i) determine how this sequence functions by introducing specifically altered forms of BYDV RNA into a cell free translation system or plant cells, and monitor protein synthesis; (ii) determine the structure of the sequence and its interactions with cellular molecules; (iii) attach the sequence to desired, nonviral genes to enhance their translation in plants. This work will help us understand how the genetic code is decoded; design means of inhibiting virus infection by selectively disrupting viral protein synthesis; and improve molecular tools for genetic engineering. *** @ @ Oh +' 0 $ H l D h R:\WWUSER\TEMPLATE\NORMAL.DOT marcia steinberg marcia steinberg @ @ @ ' S u m m a r y I n f o r m a t i o n ( 9 @ ı Microsoft Word 6.0 4 e 3 e j j j j j j j 7 1 h T 4 7 j 7 j j j j ~ j j j j 1 9420806 Miller Most viruses have RNA genomes, thus translati