View source for 3ale


==A type III polyketide synthase that produces diarylheptanoid==
<StructureSection load='3ale' size='340' side='right'caption='[[3ale]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3ale]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Oryza_sativa_Japonica_Group Oryza sativa Japonica Group]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ALE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ALE 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]] 2.5&#8491;</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=3ale FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ale OCA], [https://pdbe.org/3ale PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3ale RCSB], [https://www.ebi.ac.uk/pdbsum/3ale PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3ale ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CUS_ORYSJ CUS_ORYSJ] Plant-specific type III polyketide synthase (PKS) that catalyzes the one-pot formation of the C6-C7-C6 diarylheptanoid scaffold of bisdemethoxycurcumin by the condensation of two molecules of 4-coumaroyl-CoA and one molecule of malonyl-CoA.<ref>PMID:21041675</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Curcuminoid synthase (CUS) from Oryza sativa is a plant-specific type III polyketide synthase (PKS) that catalyzes the remarkable one-pot formation of the C(6)-C(7)-C(6) diarylheptanoid scaffold of bisdemethoxycurcumin, by the condensation of two molecules of 4-coumaroyl-CoA and one molecule of malonyl-CoA. The crystal structure of O. sativa CUS was solved at 2.5-A resolution, which revealed a unique, downward expanding active-site architecture, previously unidentified in the known type III PKSs. The large active-site cavity is long enough to accommodate the two C(6)-C(3) coumaroyl units and one malonyl unit. Furthermore, the crystal structure indicated the presence of a putative nucleophilic water molecule, which forms hydrogen bond networks with Ser351-Asn142-H(2)O-Tyr207-Glu202, neighboring the catalytic Cys174 at the active-site center. These observations suggest that CUS employs unique catalytic machinery for the one-pot formation of the C(6)-C(7)-C(6) scaffold. Thus, CUS utilizes the nucleophilic water to terminate the initial polyketide chain elongation at the diketide stage. Thioester bond cleavage of the enzyme-bound intermediate generates 4-coumaroyldiketide acid, which is then kept within the downward expanding pocket for subsequent decarboxylative condensation with the second 4-coumaroyl-CoA starter, to produce bisdemethoxycurcumin. The structure-based site-directed mutants, M265L and G274F, altered the substrate and product specificities to accept 4-hydroxyphenylpropionyl-CoA as the starter to produce tetrahydrobisdemethoxycurcumin. These findings not only provide a structural basis for the catalytic machinery of CUS but also suggest further strategies toward expanding the biosynthetic repertoire of the type III PKS enzymes.

Structural basis for the one-pot formation of the diarylheptanoid scaffold by curcuminoid synthase from Oryza sativa.,Morita H, Wanibuchi K, Nii H, Kato R, Sugio S, Abe I Proc Natl Acad Sci U S A. 2010 Nov 16;107(46):19778-83. Epub 2010 Nov 1. PMID:21041675<ref>PMID:21041675</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 3ale" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Oryza sativa Japonica Group]]
[[Category: Abe I]]
[[Category: Kato R]]
[[Category: Morita H]]
[[Category: Sugio S]]