7mdh
From Proteopedia
(New page: 200px<br /><applet load="7mdh" size="450" color="white" frame="true" align="right" spinBox="true" caption="7mdh, resolution 2.40Å" /> '''STRUCTURAL BASIS FOR...) |
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| - | [[Image:7mdh.gif|left|200px]]<br /><applet load="7mdh" size=" | + | [[Image:7mdh.gif|left|200px]]<br /><applet load="7mdh" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="7mdh, resolution 2.40Å" /> | caption="7mdh, resolution 2.40Å" /> | ||
'''STRUCTURAL BASIS FOR LIGHT ACITVATION OF A CHLOROPLAST ENZYME. THE STRUCTURE OF SORGHUM NADP-MALATE DEHYDROGENASE IN ITS OXIDIZED FORM'''<br /> | '''STRUCTURAL BASIS FOR LIGHT ACITVATION OF A CHLOROPLAST ENZYME. THE STRUCTURE OF SORGHUM NADP-MALATE DEHYDROGENASE IN ITS OXIDIZED FORM'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Some key chloroplast enzymes are activated by light via a | + | Some key chloroplast enzymes are activated by light via a ferredoxin-thioredoxin reduction system which reduces disulfide bridges in the enzymes. We describe for the first time the structural basis for the redox activation of a chloroplast enzyme, the NADP-dependent malate dehydrogenase (MDH) from Sorghum vulgare whose structure has been determined and refined at 2.4 A resolution. In addition to the normal structural components of MDHs, the enzyme exhibits extensions at both the N- and C-termini, each of which contains a regulatory disulfide bridge which must be reduced for activation. The N-terminal disulfide motif is inserted in a cleft between the two subunits of the dimer, thereby locking the domains in each subunit. The C-terminal disulfide keeps the C-terminal residues tight to the enzyme surface and blocks access to the active site. Reduction of the N-terminal disulfide would release the stopper between the domains and give the enzyme the necessary flexibility. Simultaneous reduction of the C-terminal disulfide would free the C-terminal residues from binding to the enzyme and make the active site accessible. |
==About this Structure== | ==About this Structure== | ||
| - | 7MDH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sorghum_bicolor Sorghum bicolor] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Malate_dehydrogenase_(NADP(+)) Malate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.82 1.1.1.82] Full crystallographic information is available from [http:// | + | 7MDH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sorghum_bicolor Sorghum bicolor] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Malate_dehydrogenase_(NADP(+)) Malate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.82 1.1.1.82] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7MDH OCA]. |
==Reference== | ==Reference== | ||
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[[Category: chloroplastic malate dehydrogenase (nadp+)]] | [[Category: chloroplastic malate dehydrogenase (nadp+)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:17:25 2008'' |
Revision as of 17:17, 21 February 2008
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STRUCTURAL BASIS FOR LIGHT ACITVATION OF A CHLOROPLAST ENZYME. THE STRUCTURE OF SORGHUM NADP-MALATE DEHYDROGENASE IN ITS OXIDIZED FORM
Overview
Some key chloroplast enzymes are activated by light via a ferredoxin-thioredoxin reduction system which reduces disulfide bridges in the enzymes. We describe for the first time the structural basis for the redox activation of a chloroplast enzyme, the NADP-dependent malate dehydrogenase (MDH) from Sorghum vulgare whose structure has been determined and refined at 2.4 A resolution. In addition to the normal structural components of MDHs, the enzyme exhibits extensions at both the N- and C-termini, each of which contains a regulatory disulfide bridge which must be reduced for activation. The N-terminal disulfide motif is inserted in a cleft between the two subunits of the dimer, thereby locking the domains in each subunit. The C-terminal disulfide keeps the C-terminal residues tight to the enzyme surface and blocks access to the active site. Reduction of the N-terminal disulfide would release the stopper between the domains and give the enzyme the necessary flexibility. Simultaneous reduction of the C-terminal disulfide would free the C-terminal residues from binding to the enzyme and make the active site accessible.
About this Structure
7MDH is a Single protein structure of sequence from Sorghum bicolor with as ligand. Active as Malate dehydrogenase (NADP(+)), with EC number 1.1.1.82 Full crystallographic information is available from OCA.
Reference
Structural basis for light activation of a chloroplast enzyme: the structure of sorghum NADP-malate dehydrogenase in its oxidized form., Johansson K, Ramaswamy S, Saarinen M, Lemaire-Chamley M, Issakidis-Bourguet E, Miginiac-Maslow M, Eklund H, Biochemistry. 1999 Apr 6;38(14):4319-26. PMID:10194350
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