View source for 1xg4


==Crystal Structure of the C123S 2-Methylisocitrate Lyase Mutant from Escherichia coli in complex with the inhibitor isocitrate==
<StructureSection load='1xg4' size='340' side='right'caption='[[1xg4]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1xg4]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XG4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1XG4 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=ICT:ISOCITRIC+ACID'>ICT</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=1xg4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1xg4 OCA], [https://pdbe.org/1xg4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1xg4 RCSB], [https://www.ebi.ac.uk/pdbsum/1xg4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1xg4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PRPB_ECOLI PRPB_ECOLI] Catalyzes the formation of pyruvate and succinate from 2-methylisocitrate.<ref>PMID:11422389</ref> <ref>PMID:15723538</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/xg/1xg4_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=1xg4 ConSurf].
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== Publication Abstract from PubMed ==
Two crystal structures of the C123S mutant of 2-methylisocitrate lyase have been determined, one with the bound reaction products, Mg(2+)-pyruvate and succinate, and the second with a bound Mg(2+)-(2R,3S)-isocitrate inhibitor. Comparison with the structure of the wild-type enzyme in the unbound state reveals that the enzyme undergoes a conformational transition that sequesters the ligand from solvent, as previously observed for two other enzyme superfamily members, isocitrate lyase and phosphoenolpyruvate mutase. The binding modes reveal the determinants of substrate specificity and stereoselectivity, and the stringent specificity is verified in solution using various potential substrates. A model of bound 2-methylisocitrate has been developed based on the experimentally determined structures. We propose a catalytic mechanism involving an alpha-carboxy-carbanion intermediate/transition state, which is consistent with previous stereochemical experiments showing inversion of configuration at the C(3) of 2-methylisocitrate. Structure-based sequence analysis and phylogenic tree construction reveal determinants of substrate specificity, highlight nodes of divergence of families, and predict enzyme families with new functions.

Crystal structures of 2-methylisocitrate lyase in complex with product and with isocitrate inhibitor provide insight into lyase substrate specificity, catalysis and evolution.,Liu S, Lu Z, Han Y, Melamud E, Dunaway-Mariano D, Herzberg O Biochemistry. 2005 Mar 1;44(8):2949-62. PMID:15723538<ref>PMID:15723538</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: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Dunaway-Mariano D]]
[[Category: Han Y]]
[[Category: Herzberg O]]
[[Category: Liu S]]
[[Category: Lu Z]]
[[Category: Melamud E]]