View source for 5nd5


==Crystal structure of transketolase from Chlamydomonas reinhardtii in complex with TPP and Mg2+==
<StructureSection load='5nd5' size='340' side='right'caption='[[5nd5]], [[Resolution|resolution]] 1.74&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5nd5]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Chlamydomonas_reinhardtii Chlamydomonas reinhardtii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5ND5 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5ND5 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]] 1.74&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=TPP:THIAMINE+DIPHOSPHATE'>TPP</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=5nd5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5nd5 OCA], [https://pdbe.org/5nd5 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5nd5 RCSB], [https://www.ebi.ac.uk/pdbsum/5nd5 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5nd5 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A8IAN1_CHLRE A8IAN1_CHLRE] 
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== Publication Abstract from PubMed ==
BACKGROUND: In photosynthetic organisms, transketolase (TK) is involved in the Calvin-Benson cycle and participates to the regeneration of ribulose-5-phosphate. Previous studies demonstrated that TK catalysis is strictly dependent on thiamine pyrophosphate (TPP) and divalent ions such as Mg2+. METHODS: TK from the unicellular green alga Chlamydomonas reinhardtii (CrTK) was recombinantly produced and purified to homogeneity. Biochemical properties of the CrTK enzyme were delineated by activity assays and its structural features determined by CD analysis and X-ray crystallography. RESULTS: CrTK is homodimeric and its catalysis depends on the reconstitution of the holo-enzyme in the presence of both TPP and Mg2+. Activity measurements and CD analysis revealed that the formation of fully active holo-CrTK is Mg2+-dependent and proceeds with a slow kinetics. The 3D-structure of CrTK without cofactors (CrTKapo) shows that two portions of the active site are flexible and disordered while they adopt an ordered conformation in the holo-form. Oxidative treatments revealed that Mg2+ participates in the redox control of CrTK by changing its propensity to be inactivated by oxidation. Indeed, the activity of holo-form is unaffected by oxidation whereas CrTK in the apo-form or reconstituted with the sole TPP show a strong sensitivity to oxidative inactivation. CONCLUSION: These evidences indicate that Mg2+ is fundamental to allow gradual conformational arrangements suited for optimal catalysis. Moreover, Mg2+ is involved in the control of redox sensitivity of CrTK. GENERAL SIGNIFICANCE: The importance of Mg2+ in the functionality and redox sensitivity of CrTK is correlated to light-dependent fluctuations of Mg2+ in chloroplasts.

Structural basis for the magnesium-dependent activation of transketolase from Chlamydomonas reinhardtii.,Pasquini M, Fermani S, Tedesco D, Sciabolini C, Crozet P, Naldi M, Henri J, Vothknecht U, Bertucci C, Lemaire SD, Zaffagnini M, Francia F Biochim Biophys Acta. 2017 Aug;1861(8):2132-2145. doi:, 10.1016/j.bbagen.2017.05.021. Epub 2017 May 24. PMID:28552632<ref>PMID:28552632</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 5nd5" style="background-color:#fffaf0;"></div>

==See Also==
*[[Transketolase 3D structures|Transketolase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Chlamydomonas reinhardtii]]
[[Category: Large Structures]]
[[Category: Fermani S]]
[[Category: Francia F]]
[[Category: Pasquini M]]
[[Category: Zaffagnini M]]