2h1g

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(New page: 200px<br /><applet load="2h1g" size="450" color="white" frame="true" align="right" spinBox="true" caption="2h1g, resolution 3.100&Aring;" /> '''ResA C74A/C77A'''<b...)
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[[Image:2h1g.gif|left|200px]]<br /><applet load="2h1g" size="350" color="white" frame="true" align="right" spinBox="true"
caption="2h1g, resolution 3.100&Aring;" />
caption="2h1g, resolution 3.100&Aring;" />
'''ResA C74A/C77A'''<br />
'''ResA C74A/C77A'''<br />
==Overview==
==Overview==
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ResA, an extracytoplasmic thioredoxin from Bacillus subtilis, acts in, cytochrome c maturation by reducing the disulfide bond present in, apocytochromes prior to covalent attachment of heme. This reaction is (and, has to be) specific, as broad substrate specificity would result in, unproductive shortcircuiting with the general oxidizing thioredoxin(s), present in the same compartment. Using mutational analysis and subsequent, biochemical and structural characterization of active site variants, we, show that reduced ResA displays unusually low reactivity at neutral pH, consistent with the observed high pKa values&gt;8 for both active site, cysteines. Residue Glu80 is shown to play a key role in controlling the, acid-base properties of the active site. A model in which substrate, binding dramatically enhances the reactivity of the active site cysteines, is proposed to account for the specificity of the protein. Such a, substratemediated activation mechanism is likely to have wide relevance, for extracytoplasmic thioredoxins.
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ResA, an extracytoplasmic thioredoxin from Bacillus subtilis, acts in cytochrome c maturation by reducing the disulfide bond present in apocytochromes prior to covalent attachment of heme. This reaction is (and has to be) specific, as broad substrate specificity would result in unproductive shortcircuiting with the general oxidizing thioredoxin(s) present in the same compartment. Using mutational analysis and subsequent biochemical and structural characterization of active site variants, we show that reduced ResA displays unusually low reactivity at neutral pH, consistent with the observed high pKa values&gt;8 for both active site cysteines. Residue Glu80 is shown to play a key role in controlling the acid-base properties of the active site. A model in which substrate binding dramatically enhances the reactivity of the active site cysteines is proposed to account for the specificity of the protein. Such a substratemediated activation mechanism is likely to have wide relevance for extracytoplasmic thioredoxins.
==About this Structure==
==About this Structure==
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2H1G is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2H1G OCA].
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2H1G is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2H1G OCA].
==Reference==
==Reference==
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[[Category: Bacillus subtilis]]
[[Category: Bacillus subtilis]]
[[Category: Single protein]]
[[Category: Single protein]]
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[[Category: Brun, N.E.Le.]]
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[[Category: Brun, N E.Le.]]
[[Category: Crow, A.]]
[[Category: Crow, A.]]
[[Category: Lewin, A.]]
[[Category: Lewin, A.]]
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[[Category: thioredoxin]]
[[Category: thioredoxin]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 11:30:04 2007''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:37:13 2008''

Revision as of 15:37, 21 February 2008

Image:2h1g.gif

2h1g, resolution 3.100Å

Drag the structure with the mouse to rotate

ResA C74A/C77A

Overview

ResA, an extracytoplasmic thioredoxin from Bacillus subtilis, acts in cytochrome c maturation by reducing the disulfide bond present in apocytochromes prior to covalent attachment of heme. This reaction is (and has to be) specific, as broad substrate specificity would result in unproductive shortcircuiting with the general oxidizing thioredoxin(s) present in the same compartment. Using mutational analysis and subsequent biochemical and structural characterization of active site variants, we show that reduced ResA displays unusually low reactivity at neutral pH, consistent with the observed high pKa values>8 for both active site cysteines. Residue Glu80 is shown to play a key role in controlling the acid-base properties of the active site. A model in which substrate binding dramatically enhances the reactivity of the active site cysteines is proposed to account for the specificity of the protein. Such a substratemediated activation mechanism is likely to have wide relevance for extracytoplasmic thioredoxins.

About this Structure

2H1G is a Single protein structure of sequence from Bacillus subtilis. Full crystallographic information is available from OCA.

Reference

Molecular basis for specificity of the extracytoplasmic thioredoxin ResA., Lewin A, Crow A, Oubrie A, Le Brun NE, J Biol Chem. 2006 Nov 17;281(46):35467-77. Epub 2006 Sep 13. PMID:16971393

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