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[[Image:7mdh.gif|left|200px]]
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{{STRUCTURE_7mdh|  PDB=7mdh  |  SCENE=  }}
'''STRUCTURAL BASIS FOR LIGHT ACITVATION OF A CHLOROPLAST ENZYME. THE STRUCTURE OF SORGHUM NADP-MALATE DEHYDROGENASE IN ITS OXIDIZED FORM'''


==STRUCTURAL BASIS FOR LIGHT ACITVATION OF A CHLOROPLAST ENZYME. THE STRUCTURE OF SORGHUM NADP-MALATE DEHYDROGENASE IN ITS OXIDIZED FORM==
<StructureSection load='7mdh' size='340' side='right'caption='[[7mdh]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7mdh]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Sorghum_bicolor Sorghum bicolor]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7MDH OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7MDH FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=7mdh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7mdh OCA], [https://pdbe.org/7mdh PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7mdh RCSB], [https://www.ebi.ac.uk/pdbsum/7mdh PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7mdh ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/MDHP1_SORBI MDHP1_SORBI] The chloroplastic, NADP-dependent form is essential for the photosynthesis C4 cycle, which allows plants to circumvent the problem of photorespiration. In C4 plants, NADP-MDH activity acts to convert oxaloacetate to malate in chloroplasts of mesophyll cells for transport to the bundle sheath cells.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/md/7mdh_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=7mdh ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
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.


==Overview==
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<ref>PMID:10194350</ref>
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==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
7MDH is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Sorghum_bicolor Sorghum bicolor]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7MDH OCA].
</div>
<div class="pdbe-citations 7mdh" style="background-color:#fffaf0;"></div>


==Reference==
==See Also==
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:[http://www.ncbi.nlm.nih.gov/pubmed/10194350 10194350]
*[[Malate Dehydrogenase 3D structures|Malate Dehydrogenase 3D structures]]
[[Category: Single protein]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Sorghum bicolor]]
[[Category: Sorghum bicolor]]
[[Category: Eklund, H.]]
[[Category: Eklund H]]
[[Category: Issakidis-Bourguet, E.]]
[[Category: Issakidis-Bourguet E]]
[[Category: Johansson, K.]]
[[Category: Johansson K]]
[[Category: Lemaire-Chamley, M.]]
[[Category: Lemaire-Chamley M]]
[[Category: Miginiac-Maslow, M.]]
[[Category: Miginiac-Maslow M]]
[[Category: Ramaswamy, S.]]
[[Category: Ramaswamy S]]
[[Category: Saarinen, M.]]
[[Category: Saarinen M]]
[[Category: Activated by light]]
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Retrieved from "https://proteopedia.org/7mdh"