; 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:WWUSERTEMPLATENORMAL.DOT marcia steinberg marcia steinberg @ @ @ ' S u m m a r y I n f o r m a t i o n ( 9 @ ? 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
