Biochemistry of Proteins & Metabolite Profiling

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Head: Thomas Vogt

The diversity of secondary metabolites is based on a rather limited set of biosynthetic pathways, such as phenylpropanoid or terpenoid biosynthesis. Diversification of the initial set of metabolites is initiated by modification steps like hydroxylation and further diversified by glycosylation, methylation and other transferase reactions. Therefore, the corresponding enzymes play the decisive role in the observed structural variation. Small structural differences result in the required fine tuning and the unique specificities of each enzyme which may result in completely different product properties even if the same set of substrates were used. We are currently working on three major subtypes of modifying enzymes, the glycosyl- (GTs), the S-adenosyl-L-methionine dependent O-methyl- (OMTs) and the hydroxycinnamic acid (HCA)-transferases. Our main approach combines classical enzymology and protein purification with molecular techniques and cell biology to elaborate three major research topics:

1. The biochemical and structural characteristics essential for the observed substrate promiscuity and position preference of individual subtypes. This aspect is linked to applications of these enzymes as specific catalysts in biotechnology.
2. The apparent redundancy with respect to the substrate and product profile in vitro as compared with their in vivo role.
3. The effects of selectively manipulating individual enzymes on the metabolite profile level and composition in transgenic or RNAi-suppressed plants. Fingerprint at the transcript, protein and metabolite level.
4. RP-HPLC-, GC/MS- and LC/MS/MS-based profiling of secondary metabolites in wildtype and transgenic members of Brassicaceae, Fabaceae and Solanaceae.