Information on EC 1.14.99.57 - heme oxygenase (mycobilin-producing)

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The expected taxonomic range for this enzyme is: Bacteria, Eukaryota

EC NUMBER
COMMENTARY hide
1.14.99.57
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RECOMMENDED NAME
GeneOntology No.
heme oxygenase (mycobilin-producing)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
protoheme + 3 reduced acceptor + 3 O2 = mycobilin a + Fe2+ + 3 acceptor + 3 H2O
show the reaction diagram
(1)
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protoheme + 3 reduced acceptor + 3 O2 = mycobilin b + Fe2+ + 3 acceptor + 3 H2O
show the reaction diagram
(2)
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
heme degradation VII
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SYSTEMATIC NAME
IUBMB Comments
protoheme,donor:oxygen oxidoreductase (mycobilin-producing)
The enzyme, characterized from the bacterium Mycobacterium tuberculosis, is involved in heme degradation and iron utilization. The enzyme binds two stacked protoheme molecules per monomer. Unlike the canonical heme oxygenases, the enzyme does not release carbon monoxide or formaldehyde. Instead, it forms unique products, named mycobilins, that retain the alpha-meso-carbon at the ring cleavage site as an aldehyde group. EC 1.6.2.4, NADPH-hemoprotein reductase, can act as electron donor in vitro.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
protoheme + 3 reduced acceptor + 3 O2
mycobilin a + Fe2+ + 3 acceptor + 3 H2O
show the reaction diagram
protoheme + 3 reduced acceptor + 3 O2
mycobilin b + Fe2+ + 3 acceptor + 3 H2O
show the reaction diagram
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
protoheme + 3 reduced acceptor + 3 O2
mycobilin a + Fe2+ + 3 acceptor + 3 H2O
show the reaction diagram
protoheme + 3 reduced acceptor + 3 O2
mycobilin b + Fe2+ + 3 acceptor + 3 H2O
show the reaction diagram
additional information
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
cyanide-inhibited MhuD in complex with heme as well as detailed characterization of this species. There is no evidence for an ordered network of water molecules on the distal side of the heme substrate. The degree of heme ruffling in the crystal structure is greater than that observed for heme oxygenases and less than that observed for heme-degrading enzyme IsdI. The Fe 3dxz-, 3dyz-, and 3dxy-based molecular orbitals are very close in energy, and the room-temperature 1H NMR spectrum is consistent with population of both a 2Eg electronic state with a (dxy)2(dxz,dyz)3 electron configuration, and a 2B2g state with a (dxz,dyz)4(dxy)1 electron configuration. MhuD-heme-CN has a 2B2g electronic ground state with a low-lying 2Eg excited state
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MhuD-diheme complex, to 1.75 A resolution, reveals two stacked hemes forming extensive contacts with residues in the active site. The solvent-exposed heme is axially liganded by His75 and is stacked planar upon the solvent-protected heme. The solvent-protected heme is coordinated by a chloride ion which is, in turn, stabilized by residue Asn7
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the catalytically active 1:1 heme-MhuD complex has an active site structure similar to those of heme degrading enzymes IsdG and IsdI, including the nonplanarity (ruffling) of the heme group bound to the enzyme
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
W66A
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steric bulk at residue 66 promotes MhuD-catalyzed heme oxygenation, and this reaction does not depend upon the generation of free peroxide. The protein fold is similar to wild-type
W66F
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steric bulk at residue 66 promotes MhuD-catalyzed heme oxygenation, and this reaction does not depend upon the generation of free peroxide. The protein fold is similar to wild-type
W66A
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steric bulk at residue 66 promotes MhuD-catalyzed heme oxygenation, and this reaction does not depend upon the generation of free peroxide. The protein fold is similar to wild-type
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W66F
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steric bulk at residue 66 promotes MhuD-catalyzed heme oxygenation, and this reaction does not depend upon the generation of free peroxide. The protein fold is similar to wild-type
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