View source for 2gci


==The 1,1-proton transfer reaction mechanism by alpha-methylacyl-CoA racemase is catalyzed by an asparte/histidine pair and involves a smooth, methionine-rich surface for binding the fatty acyl moiety==
<StructureSection load='2gci' size='340' side='right'caption='[[2gci]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2gci]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GCI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2GCI 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]] 1.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=MRR:(R)-2-METHYLMYRISTOYL-COENZYME+A'>MRR</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=2gci FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2gci OCA], [https://pdbe.org/2gci PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2gci RCSB], [https://www.ebi.ac.uk/pdbsum/2gci PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2gci ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/AMACR_MYCTU AMACR_MYCTU] Catalyzes the epimerization of (2R)- and (2S)-methylacyl-coenzyme A (CoA) thioesters (PubMed:15632186, PubMed:19854148, PubMed:26348625). Accepts as substrates a wide range of alpha-methylacyl-CoAs, including (2R)-2-methylmyristoyl-CoA and (2S)-2-methylmyristoyl-CoA, (2R)-pristanoyl-CoA and (2S)-pristanoyl-CoA, and the cholesterol esters (25R)-3-oxo-cholest-4-en-26-oyl-CoA and (25S)-3-oxo-cholest-4-en-26-oyl-CoA (PubMed:15632186, PubMed:26348625). Can also catalyze the interconversion of the non-physiologic substrates (2R)-ibuprofenoyl-CoA and (2S)-ibuprofenoyl-CoA, which are potential competitive inhibitors of the enzyme (PubMed:19854148).<ref>PMID:15632186</ref> <ref>PMID:19854148</ref> <ref>PMID:26348625</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/gc/2gci_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=2gci ConSurf].
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== Publication Abstract from PubMed ==
Alpha-methylacyl-CoA racemases are essential enzymes for branched-chain fatty acid metabolism. Their reaction mechanism and the structural basis of their wide substrate specificity are poorly understood. High-resolution crystal structures of Mycobacterium tuberculosis alpha-methylacyl-CoA racemase (MCR) complexed with substrate molecules show the active site geometry required for catalysis of the interconversion of (2S) and (2R)-methylacyl-CoA. The thioester oxygen atom and the 2-methyl group are in a cis-conformation with respect to each other. The thioester oxygen atom fits into an oxyanion hole and the 2-methyl group points into a hydrophobic pocket. The active site geometry agrees with a 1,1-proton transfer mechanism in which the acid/base-pair residues are His126 and Asp156. The structures of the complexes indicate that the acyl chains of the S-substrate and the R-substrate bind in an S-pocket and an R-pocket, respectively. A unique feature of MCR is a large number of methionine residues in the acyl binding region, located between the S-pocket and the R-pocket. It appears that the (S) to (R) interconversion of the 2-methylacyl chiral center is coupled to a movement of the acyl group over this hydrophobic, methionine-rich surface, when moving from its S-pocket to its R-pocket, whereas the 2-methyl moiety and the CoA group remain fixed in their respective pockets.

The catalysis of the 1,1-proton transfer by alpha-methyl-acyl-CoA racemase is coupled to a movement of the fatty acyl moiety over a hydrophobic, methionine-rich surface.,Bhaumik P, Schmitz W, Hassinen A, Hiltunen JK, Conzelmann E, Wierenga RK J Mol Biol. 2007 Apr 6;367(4):1145-61. Epub 2007 Jan 27. PMID:17320106<ref>PMID:17320106</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Mycobacterium tuberculosis]]
[[Category: Bhaumik P]]
[[Category: Wierenga RK]]