2gwc
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(New page: 200px<br /><applet load="2gwc" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gwc, resolution 2.18Å" /> '''Crystal structure of...)
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Revision as of 09:18, 21 November 2007
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Crystal structure of plant glutamate cysteine ligase in complex with a transition state analogue
Overview
Glutathione (GSH) plays a crucial role in plant metabolism and stress, response. The rate-limiting step in the biosynthesis of GSH is catalyzed, by glutamate cysteine ligase (GCL) the activity of which is tightly, regulated. The regulation of plant GCLs is poorly understood. The crystal, structure of substrate-bound GCL from Brassica juncea at 2.1-A resolution, reveals a plant-unique regulatory mechanism based on two intramolecular, redox-sensitive disulfide bonds. Reduction of one disulfide bond allows a, beta-hairpin motif to shield the active site of B. juncea GCL, thereby, preventing the access of substrates. Reduction of the second disulfide, bond reversibly controls dimer to monomer transition of B. juncea GCL that, is associated with a significant inactivation of the enzyme. These, regulatory events provide a molecular link between high GSH levels in the, plant cell and associated down-regulation of its biosynthesis., Furthermore, known mutations in the Arabidopsis GCL gene affect residues, in the close proximity of the active site and thus explain the decreased, GSH levels in mutant plants. In particular, the mutation in rax1-1 plants, causes impaired binding of cysteine.
About this Structure
2GWC is a Single protein structure of sequence from Brassica juncea with MG and BSC as ligands. Active as Glutamate--cysteine ligase, with EC number 6.3.2.2 Full crystallographic information is available from OCA.
Reference
Structural basis for the redox control of plant glutamate cysteine ligase., Hothorn M, Wachter A, Gromes R, Stuwe T, Rausch T, Scheffzek K, J Biol Chem. 2006 Sep 15;281(37):27557-65. Epub 2006 Jun 9. PMID:16766527
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