Ribosomal proteins and heterogeneity of the plant ribosome

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Arabidopsis is a small plant, in the same family as canola, whose genome was sequenced in 2000. The ribosome is a small cellular machine that assists in the conversion of genetic information into proteins in all cells. The Arabidopsis ribosome is comprised of 80 ribosomal proteins (rps - encoded by 247 genes) and four ribosomal RNAs (rRNAs) arranged in two subunits, one large and one small. Ribosome function is dependent upon roughly equimolar association of each rp and rRNA. My research programme is focused on determining the signals required for coordinated expression of the rRNAs and rps. I am particularly interested in the rps S15a (S - small subunit) and L23a (L - large subunit). S15a is required to bind to its rRNA first and thereby prime the rRNA for the addition of subsequent rps until the small subunit is assembled. L23a is an important rp linking the large subunit of the ribosome to the protein secretary pathway in all cells. Unlike yeast and animals, slightly different variations (isoforms) of each plant rp can be made in each cell. I am interested in determining what cellular cues regulate which isoform is produced in which tissue or, if more than one isoform is produced at a time, how does the resulting heterogeneity of the ribosomes within a plant cell effect the functionality of that cell. Perturbing rp production impacts ribosome assembly and function and as such can effect the rate at which plants grow and develop. Therefore, understanding how rp genes are regulated is an important aspect of the broader goal of how the development of agronomically important crop species might be manipulated to our advantage.