View source for 4a00


==Structure of an engineered aspartate aminotransferase==
<StructureSection load='4a00' size='340' side='right'caption='[[4a00]], [[Resolution|resolution]] 2.34&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4a00]] is a 1 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=4A00 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4A00 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]] 2.34&#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=PEG:DI(HYDROXYETHYL)ETHER'>PEG</scene>, <scene name='pdbligand=PP3:ALANYL-PYRIDOXAL-5-PHOSPHATE'>PP3</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=4a00 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4a00 OCA], [https://pdbe.org/4a00 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4a00 RCSB], [https://www.ebi.ac.uk/pdbsum/4a00 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4a00 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/AAT_ECOLI AAT_ECOLI] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The joint substitution of three active-site residues in Escherichia colil-aspartate aminotransferase increases the ratio of l-cysteine sulfinate desulfinase to transaminase activity 10(5)-fold. This change in reaction specificity results from combining a tyrosine-shift double mutation (Y214Q/R280Y) with a non-conservative substitution of a substrate-binding residue (I33Q). Tyr214 hydrogen bonds with O3 of the cofactor and is close to Arg374 which binds the alpha-carboxylate group of the substrate; Arg280 interacts with the distal carboxylate group of the substrate; and Ile33 is part of the hydrophobic patch near the entrance to the active site, presumably participating in the domain closure essential for the transamination reaction. In the triple-mutant enzyme, k(cat)' for desulfination of l-cysteine sulfinate increased to 0.5s(-1) (from 0.05s(-1) in wild-type enzyme), whereas k(cat)' for transamination of the same substrate was reduced from 510s(-1) to 0.05s(-1). Similarly, k(cat)' for beta-decarboxylation of l-aspartate increased from&lt;0.0001s(-1) to 0.07s(-1), whereas k(cat)' for transamination was reduced from 530s(-1) to 0.13s(-1). l-Aspartate aminotransferase had thus been converted into an l-cysteine sulfinate desulfinase that catalyzes transamination and l-aspartate beta-decarboxylation as side reactions. The X-ray structures of the engineered l-cysteine sulfinate desulfinase in its pyridoxal-5'-phosphate and pyridoxamine-5'-phosphate form or liganded with a covalent coenzyme-substrate adduct identified the subtle structural changes that suffice for generating desulfinase activity and concomitantly abolishing transaminase activity toward dicarboxylic amino acids. Apparently, the triple mutation impairs the domain closure thus favoring reprotonation of alternative acceptor sites in coenzyme-substrate intermediates by bulk water.

Structure and mechanism of a cysteine sulfinate desulfinase engineered on the aspartate aminotransferase scaffold.,Fernandez FJ, de Vries D, Pena-Soler E, Coll M, Christen P, Gehring H, Vega MC Biochim Biophys Acta. 2011 Nov 23;1824(2):339-349. PMID:22138634<ref>PMID:22138634</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4a00" style="background-color:#fffaf0;"></div>

==See Also==
*[[Aspartate aminotransferase 3D structures|Aspartate aminotransferase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Christen P]]
[[Category: Coll M]]
[[Category: Fernandez FJ]]
[[Category: Gehring H]]
[[Category: Pena-Soler E]]
[[Category: Vega MC]]
[[Category: DeVries D]]