Department of Biochemistry
Seed proteomics; seed development, oilseed metabolism, plant metabolic pathways and metabolic engineering, protein biochemistry, genomic and proteomic approaches towards understanding plant metabolism.
Plant seeds are an important renewable source of biosynthetic polymers including protein, starch, oil and fiber. The amount of these biosynthates in harvested seed varies from negligible to a majority of total mass. The model oilseed plant Arabidopsis thaliana accumulates 31-39% of seed mass as storage oil in the form of triacylglcyerol. Though the biosynthetic pathways for seed storage compounds are mostly known it is not clear how these pathways are regulated to produce higher quantities of oil versus starch, protein and fiber. A major form of regulation for metabolic pathways is gene transcription. Approaches such as anonymous sequencing of cDNA clones (White et al., 2000) and microarray technology (Girke et al., 2001) have provided global views of transcript expression in developing seeds as well as the temporal changes in the expression of these genes (Ruuska et al., 2002). A shift to this high-throughput data acquisition approach has resulted in a better understanding of the "metabolic blueprint" for an oilseed. However, it should be noted that in eukaryotes transcript expression (as determined by microarray analysis) is not always congruent with protein expression levels due to alterations in translation efficiency and protein stability. Thus a complete picture of metabolic networks in developing oilseeds will also require quantitative information about global protein expression.
With recent technological advances in the area of mass spectrometry, high throughput identification of anonymous proteins are now possible and completion of the Arabidopsis genome has positioned this plant as the model for large-scale proteomic investigations. One of the interests of my lab is in applying high-throughput proteomics towards understanding seed metabolism, particularly seeds that have evolved to accumulate oil as the primary storage reserve, such as Arabidopsis, rapeseed and sunflower. By cataloging the proteins expressed during seed development and their relative and absolute expression levels we will undoubtedly reveal biological variations from predictions based upon microarray analyses. The long term goal is to develop a model for oilseed metabolism based upon large-scale proteomic analyses. A global perspective on the temporal expression profiles of proteins in developing seeds of Arabidopsis will help reveal the dynamics of metabolic networks responsible for both oil and protein accumulation.