2gwc
From Proteopedia
(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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| - | [[Image:2gwc.gif|left|200px]]<br /><applet load="2gwc" size=" | + | [[Image:2gwc.gif|left|200px]]<br /><applet load="2gwc" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2gwc, resolution 2.18Å" /> | caption="2gwc, resolution 2.18Å" /> | ||
'''Crystal structure of plant glutamate cysteine ligase in complex with a transition state analogue'''<br /> | '''Crystal structure of plant glutamate cysteine ligase in complex with a transition state analogue'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Glutathione (GSH) plays a crucial role in plant metabolism and stress | + | 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== | ==About this Structure== | ||
| - | 2GWC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Brassica_juncea Brassica juncea] with MG and BSC as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glutamate--cysteine_ligase Glutamate--cysteine ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.2.2 6.3.2.2] Full crystallographic information is available from [http:// | + | 2GWC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Brassica_juncea Brassica juncea] with <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=BSC:'>BSC</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glutamate--cysteine_ligase Glutamate--cysteine ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.2.2 6.3.2.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GWC OCA]. |
==Reference== | ==Reference== | ||
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[[Category: redox regulation]] | [[Category: redox regulation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:36:08 2008'' |
Revision as of 15:36, 21 February 2008
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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 and 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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