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1zcp

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[[Image:1zcp.gif|left|200px]]
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{{STRUCTURE_1zcp| PDB=1zcp | SCENE= }}
{{STRUCTURE_1zcp| PDB=1zcp | SCENE= }}
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'''Crystal Structure of a catalytic site mutant E. coli TrxA (CACA)'''
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===Crystal Structure of a catalytic site mutant E. coli TrxA (CACA)===
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==Overview==
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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.
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The line below this paragraph, {{ABSTRACT_PUBMED_15987909}}, adds the Publication Abstract to the page
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(as it appears on PubMed at http://www.pubmed.gov), where 15987909 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15987909}}
==About this Structure==
==About this Structure==
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==Reference==
==Reference==
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:[http://www.ncbi.nlm.nih.gov/pubmed/15987909 15987909]
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:[http://www.ncbi.nlm.nih.gov/pubmed/15987909 15987909]
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An engineered pathway for the formation of protein disulfide bonds., Masip L, Pan JL, Haldar S, Penner-Hahn JE, DeLisa MP, Georgiou G, Bardwell JC, Collet JF, Science. 2004 Feb 20;303(5661):1185-9. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/14976313 14976313]
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Single protein]]
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[[Category: Xu, Z.]]
[[Category: Xu, Z.]]
[[Category: Electron transport]]
[[Category: Electron transport]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:28:09 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 22:02:07 2008''

Revision as of 19:02, 27 July 2008

Image:1zcp.png

Template:STRUCTURE 1zcp

Crystal Structure of a catalytic site mutant E. coli TrxA (CACA)

Template:ABSTRACT PUBMED 15987909

About this Structure

1ZCP is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

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

An engineered pathway for the formation of protein disulfide bonds., Masip L, Pan JL, Haldar S, Penner-Hahn JE, DeLisa MP, Georgiou G, Bardwell JC, Collet JF, Science. 2004 Feb 20;303(5661):1185-9. PMID:14976313

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