PROSITE documentation PDOC00512Heme oxygenase signature
Heme oxygenase (EC 1.14.99.3) (HO) [1] is the microsomal enzyme that, in animals, carries out the oxidation of heme, it cleaves the heme ring at the α methene bridge to form biliverdin and carbon monoxide. Biliverdin is subsequently converted to bilirubin by biliverdin reductase.
In mammals there are three isozymes of heme oxygenase: HO-1 to HO-3. The first two isozymes differ in their tissue expression and their inducibility: HO-1 is highly inducible by its substrate heme and by various non-heme substances, while HO-2 is non-inducible. It has been suggested [2] that HO-2 could be implicated in the production of carbon monoxide in the brain where it is said to act as a neurotransmitter.
In the genome of the chloroplast of red algae as well as in cyanobacteria, there is a heme oxygenase (gene pbsA) that is the key enzyme in the synthesis of the chromophoric part of the photosynthetic antennae [3]. An heme oxygenase is also present in the bacteria Corynebacterium diphtheriae (gene hmuO), where it is involved in the acquisition of iron from the host heme [4].
There is, in the central section of these enzymes, a well conserved region centered on a histidine residue. We have used this region as a signature pattern.
Last update:May 2004 / Text revised.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Maines M.D. |
| Title | Heme oxygenase: function, multiplicity, regulatory mechanisms, and clinical applications. | |
| Source | FASEB J. 2:2557-2568(1988). | |
| PubMed ID | 3290025 |
| 2 | Authors | Barinaga M. |
| Title | Carbon monoxide: killer to brain messenger in one step. | |
| Source | Science 259:309-309(1993). | |
| PubMed ID | 8093563 |
| 3 | Authors | Richaud C. Zabulon G. |
| Title | The heme oxygenase gene (pbsA) in the red alga Rhodella violacea is discontinuous and transcriptionally activated during iron limitation. | |
| Source | Proc. Natl. Acad. Sci. U.S.A. 94:11736-11741(1997). | |
| PubMed ID | 9326680 |
| 4 | Authors | Schmitt M.P. |
| Title | Utilization of host iron sources by Corynebacterium diphtheriae: identification of a gene whose product is homologous to eukaryotic heme oxygenases and is required for acquisition of iron from heme and hemoglobin. | |
| Source | J. Bacteriol. 179:838-845(1997). | |
| PubMed ID | 9006041 |
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