Grant: Discovery Grants Program - Individual

Ribosomesare intricate molecular machines that play a central role in translating thegenetic code into proteins. In bakers yeast, assembly of the ribosomal RNArequires a large number of factors and the correct expression of 137 ribosomalprotein-coding genes the majority of which are duplicated genes. The eventsleading to the processing of pre-rRNAs, assembly and export have beenextensively studied in vertebrates and yeast, and the overall process is verywell understood. However, the mechanism regulating the expression of duplicatedribosomal protein genes and its impact on ribosome biogenesis and functionremain unclear. Recently, we discovered that the majority of the ribosomalprotein paralogs are not expressed equally and that in most cases they areexpressed in a specific ratio required for normal growth. This finding arguesagainst an equal and redundant role for the ribosomal protein genes paralogs. Inthis proposal, we aim at understanding the mechanism regulating the expressionof duplicated genes and its impact on ribosome production and function. Accordingly,we propose two specific aims: 1. Determine the mechanism regulating theexpression of duplicated ribosomal protein genes. Under this aim, we willdetermine how duplicated genes communicate to establish the overall expressionof ribosomal proteins. We have recently identified a set of inter-regulatedduplicated ribosomal genes, and we will use them as a model for this study. Theimpact of promoters, intron, transcription termination and cellularribonucleases on the expression of these paralogs will be monitored andelements that affect inter and intragene regulation will be identified. Theoutcome of this study will not only explain how the expression of ribosomalproteins is coordinated but will also help us to understand an importantcomponent of the general mechanism of gene regulation. 2. Understand theimpact of duplicated genes on ribosome biogenesis and function. Under thisaim, we will monitor the impact of changing the ratio of ribosomal proteins onribosome biogenesis, translation and cellular functions. The duplicated geneswill be overexpressed from a heterologous promoter, deleted or mutated and theimpact on the associated proteins monitored using