View source for 5kjb


==Synechocystis apocarotenoid oxygenase (ACO) mutant - Glu150Asp==
<StructureSection load='5kjb' size='340' side='right'caption='[[5kjb]], [[Resolution|resolution]] 2.81&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5kjb]] is a 5 chain structure with sequence from [https://en.wikipedia.org/wiki/Synechocystis_sp._PCC_6803_substr._Kazusa Synechocystis sp. PCC 6803 substr. Kazusa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5KJB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5KJB 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]] 2.81&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=FE2:FE+(II)+ION'>FE2</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=5kjb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5kjb OCA], [https://pdbe.org/5kjb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5kjb RCSB], [https://www.ebi.ac.uk/pdbsum/5kjb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5kjb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ACOX_SYNY3 ACOX_SYNY3] Cleaves a number of carotenals and carotenols in the all-trans configuration at the 15-15' double bond producing retinal or retinol, respectively. Also shows activity toward lycopenals and the corresponding alcohols. Does not cleave beta-carotene or lycopene.
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== Publication Abstract from PubMed ==
Carotenoid cleavage dioxygenases (CCDs) are non-heme iron-containing enzymes found in all domains of life that generate biologically important apocarotenoids. Prior studies have revealed a critical role for a conserved 4-His motif in forming the CCD iron center. By contrast, the roles of other active site residues in catalytic function including maintenance of the stringent regio- and stereo-selective cleavage activity typically exhibited by these enzymes have not been thoroughly investigated. Here we examined the functional and structural importance of active site residues in an apocarotenoid-cleaving oxygenase (ACO) from Synechocystis. Most active site substitutions variably lowered maximal catalytic activity without markedly affecting the Km value for the all-trans-8'-apocarotenol substrate. Native C15-C15' cleavage activity was retained in all ACO variants examined suggesting that multiple active site residues contribute to the enzyme's regioselectivity. Crystallographic analysis of a nearly inactive W149A-substituted ACO revealed marked disruption of the active site structure including loss of iron coordination by His-238 apparently from an altered conformation of the conserved second sphere Glu-150 residue. Gln and Asp 150-substituted versions of ACO further confirmed the structural/functional requirement for a Glu side chain at this position, which is homologous to Glu-148 in RPE65, a site in which substitution to Asp has been associated with loss of enzymatic function in Leber congenital amaurosis. The novel links shown here between ACO active site structure and catalytic activity could be broadly applicable to other CCD members and provide insights into the molecular pathogenesis of vision loss associated with an RPE65 point mutation.

Key residues for catalytic function and metal coordination in a carotenoid cleavage dioxygenase.,Sui X, Zhang J, Golczak M, Palczewski K, Kiser PD J Biol Chem. 2016 Jul 24. pii: jbc.M116.744912. PMID:27453555<ref>PMID:27453555</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 5kjb" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Synechocystis sp. PCC 6803 substr. Kazusa]]
[[Category: Kiser PD]]
[[Category: Palczewski K]]
[[Category: Sui X]]