Haem oxygenase-like, multi-helical (IPR016084)
Short name: Haem_Oase-like_multi-hlx
- Haem oxygenase (IPR002051)
- Thiaminase-2/PQQC (IPR004305)
- Coenzyme PQQ biosynthesis protein C (IPR011845)
- Haem oxygenase-like (IPR016053)
- Haem oxygenase (decyclizing), plant (IPR016951)
- Uncharacterised conserved protein UCP032676, PqqC (IPR017004)
- Protein of unknown function DUF3050 (IPR024423)
- Protein of unknown function DUF3865, CADD-like (IPR024477)
- TenA_E protein (IPR026285)
- Putative folate metabolism protein, CADD family (IPR027572)
- Thiaminase II (IPR027574)
- PqqC-like protein (IPR028201)
This superfamily represents a multi-helical structural domain consisting of two structural repeats (duplication) of a 3-helical motif. This domain can be found in both eukaryotic and prokaryotic haem oxygenases [PMID: 15049686, PMID: 11560504], in TENA/THI-4 proteins that lack the haem-binding site [PMID: 15858269], and in coenzyme PQQ (pyrrolo-quinoline-quinone) biosynthesis protein C (PqqC) [PMID: 15148379].
Haem oxygenase (EC:188.8.131.52) (HO) is the microsomal enzyme that, in animals, carries out the oxidation of haem, cleaving the haem ring at the alpha-methene bridge to form biliverdin and carbon monoxide. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. In mammals there are three isozymes of haem 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 haem and by various non-haem substances, while HO-2 is non-inducible. Haem oxygenase is also present in certain bacteria, where it is involved in the acquisition of iron from the host haem.
The THI-4 protein is involved in thiamine biosynthesis, while TENA is one of a number of proteins that enhance the expression of extracellular enzymes, such as alkaline protease, neutral protease and levansucrase.
Coenzyme PQQ (pyrrolo-quinoline-quinone) biosynthesis protein C (PqqC; EC:184.108.40.206) is required for the synthesis of PQQ, where PQQ is a prosthetic group found in several bacterial enzymes, including methanol dehydrogenase of methylotrophs and the glucose dehydrogenase of a number of bacteria.