1wnx: Difference between revisions

Revision as of 13:55, 3 May 2008

D136E mutant of Heme Oxygenase from Corynebacterium diphtheriae (HmuO)

OverviewOverview

Heme oxygenases found in mammals, plants, and bacteria catalyze degradation of heme using the same mechanism. Roles of distal Asp (Asp-136) residue in HmuO, a heme oxygenase of Corynebacterium diphtheriae, have been investigated by site-directed mutagenesis, enzyme kinetics, resonance Raman spectroscopy, and x-ray crystallography. Replacements of the Asp-136 by Ala and Phe resulted in reduced heme degradation activity due to the formation of ferryl heme, showing that the distal Asp is critical in HmuO heme oxygenase activity. D136N HmuO catalyzed heme degradation at a similar efficiency to wild type and D136E HmuO, implying that the carboxylate moiety is not required for the heme catabolism by HmuO. Resonance Raman results suggest that the inactive ferryl heme formation in the HmuO mutants is induced by disruption of the interaction between a reactive Fe-OOH species and an adjacent distal pocket water molecule. Crystal structural analysis of the HmuO mutants confirms partial disappearance of this nearby water in D136A HmuO. Our results provide the first experimental evidence for the catalytic importance of the nearby water molecule that can be universally critical in heme oxygenase catalysis and propose that the distal Asp helps in positioning the key water molecule at a position suitable for efficient activation of the Fe-OOH species.

About this StructureAbout this Structure

1WNX is a Single protein structure of sequence from Corynebacterium diphtheriae. Full crystallographic information is available from OCA.

ReferenceReference

Roles of distal Asp in heme oxygenase from Corynebacterium diphtheriae, HmuO: A water-driven oxygen activation mechanism., Matsui T, Furukawa M, Unno M, Tomita T, Ikeda-Saito M, J Biol Chem. 2005 Jan 28;280(4):2981-9. Epub 2004 Nov 4. PMID:15528205 Page seeded by OCA on Sat May 3 13:55:40 2008

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

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 [[Image:1wnx.gif|left|200px]]
- {{Structure
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-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Heme_oxygenase Heme oxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.99.3 1.14.99.3] </span>
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-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1wnx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1wnx OCA], [http://www.ebi.ac.uk/pdbsum/1wnx PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1wnx RCSB]</span>
-}}
 '''D136E mutant of Heme Oxygenase from Corynebacterium diphtheriae (HmuO)'''
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 [[Category: Matsui, T.]]
 [[Category: Unno, M.]]
-[[Category: alpha-helix]]
+[[Category: Alpha-helix]]
-[[Category: heme]]
+[[Category: Heme]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 13:55:40 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 00:38:47 2008''