Solving the 3D-structure of plant-type y-glutamylcysteine sythetase (GSH1): Structural basis for post-translational redox control and evolutionary relationship with proteobacterial GSH1 proteins
Final Report Abstract
The tripeptide glutathione is a key component of cellular redox homeostasis and Is involved in many stress responses. Its biosynthesis is largely controlled by the plastidic enzyme gamma-glutamylcystein ligase (GCL). The first structure of a plant GCL enzyme has now been solved. This has led to the discovery of a post-translational redox regulation of plant GCL via reversible homodimer formation. While the cysteines forming the disulfide required for homodimerization are conserved in the evolutionarily related GCL enzymes from a-proteobacteria, the functional role of this disulfide bridge for dimerization is restricted to plants and may be related to the specific requirements for enzyme control in the chloroplast. Amino acid residues of the homodimer interface have been identified. The elucidation of the first plant GCL structure has also provided insight into several previously described Arabidopsis thaliana mutants with amino acid exchanges in GCL. While it is intriguing that the enzyme catalyzing the first step of the major cellular antioxidant is itself under redox control, future work will have to address the mechanism mediating the redox control of GCL, i.e. the reversible homodimerization in vivo. This work has considerably advanced our understanding of how plants control their glutathione biosynthesis.
Publications
- (2006) Structural basis for the redoxcontrol of plant glutamate cysteine ligase. J Biol Chem 281: 27557-27565
Hothorn M, Wächter A, Gromes R, Stuwe T, Rausch T, Scheffzek K
- (2007) Novel insight into the regulation of GSH biosynthesis in higher plants. Plant Biol 9, 565-572.
Rausch T, Gromes R, Liedschulte V, Müller I, Bogs J, Galovic V, Wächter A
- PhD final examination: July 2007 Title: Crystallographic studies on protein regulatory mechanisms: from the alternative splicing of ahuman chromatin component to plant enzyme regulation
Michael Hothorn
- (2008) Biosynthesis, compartmentation and cellular functions of glutathione in plant cells. In: Sulfur in phototrophic organisms (R. Hell, C. Dahl, D. Kneff, T. Leustek, eds.), Springer Verlag, Dordrecht, pp. 165-188
Meyer, A.J. and Rausch, T.
- (2008) Redox-switch of yglutamylcysteine ligase via reversible monomer-dimer transition Is a mechanism unique to plants. Plant J 54:1063-1075
Gromes R, Hothom M, Lenher E, Rybin V, Scheffzek K, Rausch T
- PhD final examination: January 2008 Title: Post-translational regulation and evolution of plant glutamate cysteine ligase
Roland Gromes
