Biogenesis of the plant ribosome and its role in plant growth and development

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Ribosomes are fundamental constituents of all living cells - natural nano-machines responsible for the conversion of the information stored as DNA in the nucleus, into proteins capable of doing work within a cell, tissue or organism.The two subunits (large: 60 S and small: 40 S) of a ribosome are together comprised of 81 proteins (ribosomal proteins: RPs) located on a scaffold of ribosomal RNA (rRNA). My research program is focused on understanding ribosome biogenesis - the making of a ribosome, in plants. For each RP, plants have in their genomes between 2 and 7 genes from which the same RP, with some degree of variation in structure (an isoform), can be made. To build a ribosome, a large number of other proteins, ribosome biogenesis factors (RBFs), as well as other factors, are required. In plants, for each RBF there is again a family of genes that produce slightly different variations (isoforms) of each factor. This level of variation between isoforms suggests that within any one plant cell or tissue, the ribosome population may be homogeneous - all with the same ability to synthesis a 'house-keeping' array of proteins, or the ribosome population may be heterogeneous whereby ribosomes with different isoform compositions enable a plant to respond to changing environments (internal or external to the cell) by selectively synthesizing specialized proteins that can function within the changed environment. By having such a repertoire of ribosomes available to it, a plant is enabled to withstand a multitude of changing environmental conditions. In my research program, we are focusing on a select number of RP and RBF families, in the model dicot plant Arabidopsis, to identify the role of the family isoforms in plant ribosome biogenesis and function. The five RP families that we are initially focusing on each have two or three isoforms and the RBF family is comprised of four isoforms. We will be carrying out molecular and cellular biological, biochemical and physiological studies on the isoforms, as well as on plants carrying mutations for each isoform, to identify their role(s) in plant adaptability to changing environmental conditions.***Understanding the assembly and function of specialized ribosomes will provide us the means to engineer controlled, optimized responses of future crop plants to future climate change conditions and offer the opportunity to build ribosomes in vitro that are capable of the highly specialized synthesis of specific proteins or families of proteins.