View source for 1zcp


==Crystal Structure of a catalytic site mutant E. coli TrxA (CACA)==
<StructureSection load='1zcp' size='340' side='right'caption='[[1zcp]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1zcp]] 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=1ZCP OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1ZCP 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]] 2.3&#8491;</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=1zcp FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1zcp OCA], [https://pdbe.org/1zcp PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1zcp RCSB], [https://www.ebi.ac.uk/pdbsum/1zcp PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1zcp ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/THIO_ECOLI THIO_ECOLI] Participates in various redox reactions through the reversible oxidation of its active center dithiol to a disulfide and catalyzes dithiol-disulfide exchange reactions.
== 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/zc/1zcp_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=1zcp ConSurf].
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== Publication Abstract from PubMed ==
Escherichia coli thioredoxin is a small monomeric protein that reduces disulfide bonds in cytoplasmic proteins. Two cysteine residues present in a conserved CGPC motif are essential for this activity. Recently, we identified mutations of this motif that changed thioredoxin into a homodimer bridged by a [2Fe-2S] iron-sulfur cluster. When exported to the periplasm, these thioredoxin mutants could restore disulfide bond formation in strains lacking the entire periplasmic oxidative pathway. Essential for the assembly of the iron-sulfur was an additional cysteine that replaced the proline at position three of the CGPC motif. We solved the crystalline structure at 2.3 Angstroms for one of these variants, TrxA(CACA). The mutant protein crystallized as a dimer in which the iron-sulfur cluster is replaced by two intermolecular disulfide bonds. The catalytic site, which forms the dimer interface, crystallized in two different conformations. In one of them, the replacement of the CGPC motif by CACA has a dramatic effect on the structure and causes the unraveling of an extended alpha-helix. In both conformations, the second cysteine residue of the CACA motif is surface-exposed, which contrasts with wildtype thioredoxin where the second cysteine of the CXXC motif is buried. This exposure of a pair of vicinal cysteine residues apparently allows thioredoxin to acquire an iron-sulfur cofactor at its active site, and thus a new activity and mechanism of action.

The crystal structure of TrxA(CACA): Insights into the formation of a [2Fe-2S] iron-sulfur cluster in an Escherichia coli thioredoxin mutant.,Collet JF, Peisach D, Bardwell JC, Xu Z Protein Sci. 2005 Jul;14(7):1863-9. PMID:15987909<ref>PMID:15987909</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Thioredoxin 3D structures|Thioredoxin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Bardwell JC]]
[[Category: Collet J-F]]
[[Category: Peisach D]]
[[Category: Xu Z]]