View source for 2j2f


==The T199D Mutant of Stearoyl Acyl Carrier Protein Desaturase from Ricinus Communis (Castor Bean)==
<StructureSection load='2j2f' size='340' side='right'caption='[[2j2f]], [[Resolution|resolution]] 2.65&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2j2f]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Ricinus_communis Ricinus communis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2J2F OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2J2F 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]] 2.65&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=FE:FE+(III)+ION'>FE</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=2j2f FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2j2f OCA], [https://pdbe.org/2j2f PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2j2f RCSB], [https://www.ebi.ac.uk/pdbsum/2j2f PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2j2f ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/STAD_RICCO STAD_RICCO] Converts stearoyl-ACP to oleoyl-ACP by introduction of a cis double bond between carbons Delta(9) and Delta(10) of the acyl chain.
== 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/j2/2j2f_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=2j2f ConSurf].
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== Publication Abstract from PubMed ==
Sequence analysis of the diiron cluster-containing soluble desaturases suggests they are unrelated to other diiron enzymes; however, structural alignment of the core four-helix bundle of desaturases to other diiron enzymes reveals a conserved iron binding motif with similar spacing in all enzymes of this structural class, implying a common evolutionary ancestry. Detailed structural comparison of the castor desaturase with that of a peroxidase, rubrerythrin, shows remarkable conservation of both identity and geometry of residues surrounding the diiron center, with the exception of residue 199. Position 199 is occupied by a threonine in the castor desaturase, but the equivalent position in rubrerythrin contains a glutamic acid. We previously hypothesized that a carboxylate in this location facilitates oxidase chemistry in rubrerythrin by the close apposition of a residue capable of facilitating proton transfer to the activated oxygen (in a hydrophobic cavity adjacent to the diiron center based on the crystal structure of the oxygen-binding mimic azide). Here we report that desaturase mutant T199D binds substrate but its desaturase activity decreases by approximately 2 x 10(3)-fold. However, it shows a &gt;31-fold increase in peroxide-dependent oxidase activity with respect to WT desaturase, as monitored by single-turnover stopped-flow spectrometry. A 2.65-A crystal structure of T199D reveals active-site geometry remarkably similar to that of rubrerythrin, consistent with its enhanced function as an oxidase enzyme. That a single amino acid substitution can switch reactivity from desaturation to oxidation provides experimental support for the hypothesis that the desaturase evolved from an ancestral oxidase enzyme.

A single mutation in the castor Delta9-18:0-desaturase changes reaction partitioning from desaturation to oxidase chemistry.,Guy JE, Abreu IA, Moche M, Lindqvist Y, Whittle E, Shanklin J Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17220-4. Epub 2006 Nov 6. PMID:17088542<ref>PMID:17088542</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 2j2f" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Ricinus communis]]
[[Category: Abreu IA]]
[[Category: Guy JE]]
[[Category: Lindqvist Y]]
[[Category: Moche M]]
[[Category: Shanklin J]]
[[Category: Whittle E]]