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Crystal structure of a heme oxygenase (HmuO) from Corynebacterium diphtheriae complexed with heme in the ferrous state

OverviewOverview

Crystal structures of the ferric and ferrous heme complexes of HmuO, a 24-kDa heme oxygenase of Corynebacterium diphtheriae, have been refined to 1.4 and 1.5 A resolution, respectively. The HmuO structures show that the heme group is closely sandwiched between the proximal and distal helices. The imidazole group of His-20 is the proximal heme ligand, which closely eclipses the beta- and delta-meso axis of the porphyrin ring. A long range hydrogen bonding network is present, connecting the iron-bound water ligand to the solvent water molecule. This enables proton transfer from the solvent to the catalytic site, where the oxygen activation occurs. In comparison to the ferric complex, the proximal and distal helices move closer to the heme plane in the ferrous complex. Together with the kinked distal helix, this movement leaves only the alpha-meso carbon atom accessible to the iron-bound dioxygen. The heme pocket architecture is responsible for stabilization of the ferric hydroperoxo-active intermediate by preventing premature heterolytic O-O bond cleavage. This allows the enzyme to oxygenate selectively at the alpha-meso carbon in HmuO catalysis.

About this StructureAbout this Structure

1IW1 is a Single protein structure of sequence from Corynebacterium diphtheriae with , and as ligands. Active as Heme oxygenase, with EC number 1.14.99.3 Full crystallographic information is available from OCA.

ReferenceReference

The crystal structures of the ferric and ferrous forms of the heme complex of HmuO, a heme oxygenase of Corynebacterium diphtheriae., Hirotsu S, Chu GC, Unno M, Lee DS, Yoshida T, Park SY, Shiro Y, Ikeda-Saito M, J Biol Chem. 2004 Mar 19;279(12):11937-47. Epub 2003 Nov 26. PMID:14645223

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 '''Crystal structure of a heme oxygenase (HmuO) from Corynebacterium diphtheriae complexed with heme in the ferrous state'''<br />
 ==Overview==
-Crystal structures of the ferric and ferrous heme complexes of HmuO, a, 24-kDa heme oxygenase of Corynebacterium diphtheriae, have been refined to, 1.4 and 1.5 A resolution, respectively. The HmuO structures show that the, heme group is closely sandwiched between the proximal and distal helices., The imidazole group of His-20 is the proximal heme ligand, which closely, eclipses the beta- and delta-meso axis of the porphyrin ring. A long range, hydrogen bonding network is present, connecting the iron-bound water, ligand to the solvent water molecule. This enables proton transfer from, the solvent to the catalytic site, where the oxygen activation occurs. In, comparison to the ferric complex, the proximal and distal helices move, closer to the heme plane in the ferrous complex. Together with the kinked, distal helix, this movement leaves only the alpha-meso carbon atom, accessible to the iron-bound dioxygen. The heme pocket architecture is, responsible for stabilization of the ferric hydroperoxo-active, intermediate by preventing premature heterolytic O-O bond cleavage. This, allows the enzyme to oxygenate selectively at the alpha-meso carbon in, HmuO catalysis.
+Crystal structures of the ferric and ferrous heme complexes of HmuO, a 24-kDa heme oxygenase of Corynebacterium diphtheriae, have been refined to 1.4 and 1.5 A resolution, respectively. The HmuO structures show that the heme group is closely sandwiched between the proximal and distal helices. The imidazole group of His-20 is the proximal heme ligand, which closely eclipses the beta- and delta-meso axis of the porphyrin ring. A long range hydrogen bonding network is present, connecting the iron-bound water ligand to the solvent water molecule. This enables proton transfer from the solvent to the catalytic site, where the oxygen activation occurs. In comparison to the ferric complex, the proximal and distal helices move closer to the heme plane in the ferrous complex. Together with the kinked distal helix, this movement leaves only the alpha-meso carbon atom accessible to the iron-bound dioxygen. The heme pocket architecture is responsible for stabilization of the ferric hydroperoxo-active intermediate by preventing premature heterolytic O-O bond cleavage. This allows the enzyme to oxygenate selectively at the alpha-meso carbon in HmuO catalysis.
 ==About this Structure==
-IW1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Corynebacterium_diphtheriae Corynebacterium diphtheriae] with SUC, SO4 and HEM as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [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] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1IW1 OCA].
+IW1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Corynebacterium_diphtheriae Corynebacterium diphtheriae] with <scene name='pdbligand=SUC:'>SUC</scene>, <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IW1 OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Heme oxygenase]]
 [[Category: Single protein]]
-[[Category: Chu, G.C.]]
+[[Category: Chu, G C.]]
 [[Category: Hirotsu, S.]]
 [[Category: Ikeda-Saito, M.]]
-[[Category: Lee, D.S.]]
+[[Category: Lee, D S.]]
-[[Category: Park, S.Y.]]
+[[Category: Park, S Y.]]
-[[Category: RSGI, RIKEN.Structural.Genomics/Proteomics.Initiative.]]
+[[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]]
 [[Category: Shiro, Y.]]
 [[Category: Unno, M.]]
@@ Line 31: / Line 31: @@
 [[Category: structural genomics]]
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