Investigation of the presence of a glucosinolate metabolon

Biosynthetic proteins are hypothesized to be organized in supramolecular complexes (metabolons), which ensure that substrates are efficiently channeled into and through a pathway. At the same time, they may link to other pathways in metabolic grids e.g. in primary metabolism. Additional complexity arises from compartmentalization which requires metabolites to be shuttled efficiently between subcellularly distinct metabolons.

 

In A. thaliana, biosynthesis of the >25 Met-derived GLS is initiated by chain-elongation of Met in the chloroplast, i.e. by sequential insertion of one to six methylene groups via a cycle of three enzymatic steps. Met derivatives are exported from the chloroplast and enter the cytosolic GLS core structure biosynthesis consisting of two ER-anchored cytochrome P450s and four soluble enzymes.

 

Intermediates from the chain-elongation or core structure biosynthesis do not accumulate to detectable levels in the plant, which suggests efficient substrate channeling within and between the compartmentalized pathways. After core structure formation, GLS can undergo secondary modifications by enzymes not necessarily associated with the core pathway as both unmodified and modified GLS metabolites accumulate.

 

Accurate assembly of metabolons requires assisting factors such as scaffolding proteins and assembly chaperones. Our goal is to understand the principles of assembly/disassembly of supramolecular protein complexes and how physical interactions of proteins determine metabolite profiles in a pathway-specific context.

 

	Hypothetical glucosinolate metabolon wíth scaffolding protein.