Biochemistry and evolution of glucosinolate hydrolysis in plants - the role of specifier proteins

UTE WITTSTOCK
Institut für Pharmazeutische Biologie
Technische Universität Braunschweig
Mendelssohnstr. 1
38106 Braunschweig
u.wittstock@tu-bs.de

The diversity of the glucosinolate-myrosinase defense system arises not only from the variety of structures of parent glucosinolates, sulfur-rich thioglycosides found in plants of the Brassicaceae and some related families, but also from the multiple modes of glucosinolate hydrolysis employed by plants. Depending on the glucosinolate structure and the presence of certain protein factors, the epithiospecifier proteins (ESPs) and the thiocyanate-forming proteins (TFPs), one glucosinolate can be hydrolyzed to different products with diverse biological activities, for example, isothiocyanates, nitriles and organic thiocyanates. The goal of our project is to learn to understand, how and why plants generate diversity at the level of glucosinolate hydrolysis. The project is focused at two major questions: Which structural elements are responsible for the substrate and product specificities of ESPs/TFPs and for their interactions with myrosinases? Is there an evolutionary relationship between ESPs/TFPs and myrosinase-binding proteins (MBPs)? The structure of specifier proteins will be analyzed by mutation analysis, molecular modelling, and diffraction analysis of protein crystals. Identification and characterization of ESPs/TFPs and MBPs from various plant families will allow us to perform phylogentic sequence analyses that permit conclusions on the evolution of specifier proteins in plants. Based on these results, the mechanisms involved in the evolution of the glucosinolate-myrosinase system will be investigated.

[back]