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2hq2

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{{STRUCTURE_2hq2| PDB=2hq2 | SCENE= }}
{{STRUCTURE_2hq2| PDB=2hq2 | SCENE= }}
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'''Structure of the Escherichia coli O157:H7 Heme Oxygenase ChuS in Complex with Heme'''
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===Structure of the Escherichia coli O157:H7 Heme Oxygenase ChuS in Complex with Heme===
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==Overview==
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Heme oxygenases catalyze the oxidation of heme to biliverdin, CO, and free iron. For pathogenic microorganisms, heme uptake and degradation are critical mechanisms for iron acquisition that enable multiplication and survival within hosts they invade. Here we report the first crystal structure of the pathogenic Escherichia coli O157:H7 heme oxygenase ChuS in complex with heme at 1.45 A resolution. When compared with other heme oxygenases, ChuS has a unique fold, including structural repeats and a beta-sheet core. Not surprisingly, the mode of heme coordination by ChuS is also distinct, whereby heme is largely stabilized by residues from the C-terminal domain, assisted by a distant arginine from the N-terminal domain. Upon heme binding, there is no large conformational change beyond the fine tuning of a key histidine (His-193) residue. Most intriguingly, in contrast to other heme oxygenases, the propionic side chains of heme are orientated toward the protein core, exposing the alpha-meso carbon position where O(2) is added during heme degradation. This unique orientation may facilitate presentation to an electron donor, explaining the significantly reduced concentration of ascorbic acid needed for the reaction. Based on the ChuS-heme structure, we converted the histidine residue responsible for axial coordination of the heme group to an asparagine residue (H193N), as well as converting a second histidine to an alanine residue (H73A) for comparison purposes. We employed spectral analysis and CO measurement by gas chromatography to analyze catalysis by ChuS, H193N, and H73A, demonstrating that His-193 is the key residue for the heme-degrading activity of ChuS.
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{{ABSTRACT_PUBMED_17023414}}
==About this Structure==
==About this Structure==
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[[Category: Structural genomic]]
[[Category: Structural genomic]]
[[Category: Structural repeat]]
[[Category: Structural repeat]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 18:47:25 2008''

Revision as of 15:47, 28 July 2008

Image:2hq2.png

Template:STRUCTURE 2hq2

Structure of the Escherichia coli O157:H7 Heme Oxygenase ChuS in Complex with Heme

Template:ABSTRACT PUBMED 17023414

About this Structure

2HQ2 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Structure of the Escherichia coli O157:H7 heme oxygenase ChuS in complex with heme and enzymatic inactivation by mutation of the heme coordinating residue His-193., Suits MD, Jaffer N, Jia Z, J Biol Chem. 2006 Dec 1;281(48):36776-82. Epub 2006 Oct 5. PMID:17023414

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