View source for 1d6h


==CHALONE SYNTHASE (N336A MUTANT COMPLEXED WITH COA)==
<StructureSection load='1d6h' size='340' side='right'caption='[[1d6h]], [[Resolution|resolution]] 2.15&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1d6h]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Medicago_sativa Medicago sativa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1D6H OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1D6H 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]] 2.15&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=COA:COENZYME+A'>COA</scene>, <scene name='pdbligand=CSD:3-SULFINOALANINE'>CSD</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=1d6h FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1d6h OCA], [https://pdbe.org/1d6h PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1d6h RCSB], [https://www.ebi.ac.uk/pdbsum/1d6h PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1d6h ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CHS2_MEDSA CHS2_MEDSA] The primary product of this enzyme is 4,2',4',6'-tetrahydroxychalcone (also termed naringenin-chalcone or chalcone) which can under specific conditions spontaneously isomerize into naringenin.<ref>PMID:10653632</ref> <ref>PMID:11732902</ref> <ref>PMID:11959984</ref> <ref>PMID:15380179</ref> 
== 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/d6/1d6h_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=1d6h ConSurf].
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== Publication Abstract from PubMed ==
Chalcone synthase (CHS) catalyzes formation of the phenylpropanoid chalcone from one p-coumaroyl-CoA and three malonyl-coenzyme A (CoA) thioesters. The three-dimensional structure of CHS [Ferrer, J.-L., Jez, J. M., Bowman, M. E., Dixon, R. A., and Noel, J. P. (1999) Nat. Struct. Biol. 6, 775-784] suggests that four residues (Cys164, Phe215, His303, and Asn336) participate in the multiple decarboxylation and condensation reactions catalyzed by this enzyme. Here, we functionally characterize 16 point mutants of these residues for chalcone production, malonyl-CoA decarboxylation, and the ability to bind CoA and acetyl-CoA. Our results confirm Cys164's role as the active-site nucleophile in polyketide formation and elucidate the importance of His303 and Asn336 in the malonyl-CoA decarboxylation reaction. We suggest that Phe215 may help orient substrates at the active site during elongation of the polyketide intermediate. To better understand the structure-function relationships in some of these mutants, we also determined the crystal structures of the CHS C164A, H303Q, and N336A mutants refined to 1.69, 2.0, and 2.15 A resolution, respectively. The structure of the C164A mutant reveals that the proposed oxyanion hole formed by His303 and Asn336 remains undisturbed, allowing this mutant to catalyze malonyl-CoA decarboxylation without chalcone formation. The structures of the H303Q and N336A mutants support the importance of His303 and Asn336 in polarizing the thioester carbonyl of malonyl-CoA during the decarboxylation reaction. In addition, both of these residues may also participate in stabilizing the tetrahedral transition state during polyketide elongation. Conservation of the catalytic functions of the active-site residues may occur across a wide variety of condensing enzymes, including other polyketide and fatty acid synthases.

Dissection of malonyl-coenzyme A decarboxylation from polyketide formation in the reaction mechanism of a plant polyketide synthase.,Jez JM, Ferrer JL, Bowman ME, Dixon RA, Noel JP Biochemistry. 2000 Feb 8;39(5):890-902. PMID:10653632<ref>PMID:10653632</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 1d6h" style="background-color:#fffaf0;"></div>

==See Also==
*[[Chalcone synthase|Chalcone synthase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Medicago sativa]]
[[Category: Bowman ME]]
[[Category: Dixon RA]]
[[Category: Ferrer JL]]
[[Category: Jez JM]]
[[Category: Noel JP]]