View source for 4jad


==STRUCTURAL DETERMINATION OF THE A50T:S279G:S280K:V281K:K282E:H283N VARIANT OF CITRATE SYNTHASE from E. COLI==
<StructureSection load='4jad' size='340' side='right'caption='[[4jad]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4jad]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=3l96 3l96]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4JAD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4JAD 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]] 1.9&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><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=4jad FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4jad OCA], [https://pdbe.org/4jad PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4jad RCSB], [https://www.ebi.ac.uk/pdbsum/4jad PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4jad ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CISY_ECOLI CISY_ECOLI] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The citrate synthase (CS) of Escherichia coli is an allosteric hexameric enzyme specifically inhibited by NADH. The crystal structure of wild type (WT) E. coli CS, determined by us previously, has no substrates bound, and part of the active site is in a highly mobile region that is shifted from the position needed for catalysis. The CS of Acetobacter aceti has a similar structure, but has been successfully crystallized with bound substrates: both oxaloacetic acid (OAA) and an analog of acetyl coenzyme A (AcCoA). We engineered a variant of E. coli CS wherein five amino acids in the mobile region have been replaced by those in the A. aceti sequence. The purified enzyme shows unusual kinetics with a low affinity for both substrates. Although the crystal structure without ligands is very similar to that of the WT enzyme (except in the mutated region), complexes are formed with both substrates and the allosteric inhibitor NADH. The complex with OAA in the active site identifies a novel OAA-binding residue, Arg306, which has no functional counterpart in other known CS-OAA complexes. This structure may represent an intermediate in a multi-step substrate binding process where Arg306 changes roles from OAA binding to AcCoA binding. The second complex has the substrate analog, S-carboxymethyl-coenzyme A, in the allosteric NADH-binding site and the AcCoA site is not formed. Additional CS variants unable to bind adenylates at the allosteric site show that this second complex is not a factor in positive allosteric activation of AcCoA binding.

Enzyme-substrate complexes of allosteric citrate synthase: Evidence for a novel intermediate in substrate binding.,Duckworth HW, Nguyen NT, Gao Y, Donald LJ, Maurus R, Ayed A, Bruneau B, Brayer GD Biochim Biophys Acta. 2013 Aug 14. pii: S1570-9639(13)00291-4. doi:, 10.1016/j.bbapap.2013.07.019. PMID:23954305<ref>PMID:23954305</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4jad" style="background-color:#fffaf0;"></div>

==See Also==
*[[Citrate Synthase 3D structures|Citrate Synthase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Brayer GD]]
[[Category: Maurus R]]