1we1 | pdb_00001we1
Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC6803 in complex with heme
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| 1we1, resolution 2.5Å | |||||||||||||
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| Ligands: | CL, HEM, IPA, PO4 | ||||||||||||
| Activity: | Heme oxygenase, with EC number 1.14.99.3 | ||||||||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||||||
Overview
Heme oxygenase (HO) catalyzes the oxidative degradation of heme utilizing molecular oxygen and reducing equivalents. In photosynthetic organisms, HO functions in the biosynthesis of such open-chain tetrapyrroles as phyto-chromobilin and phycobilins, which are involved in the signal transduction for light responses and light harvesting for photosynthesis, respectively. We have determined the first crystal structure of a HO-1 from a photosynthetic organism, Synechocystis sp. PCC 6803 (Syn HO-1), in complex with heme at 2.5 A resolution. Heme-Syn HO-1 shares a common folding with other heme-HOs. Although the heme pocket of heme-Syn HO-1 is, for the most part, similar to that of mammalian HO-1, they differ in such features as the flexibility of the distal helix and hydrophobicity. In addition, 2-propanol derived from the crystallization solution occupied the hydrophobic cavity, which is proposed to be a CO trapping site in rat HO-1 that suppresses product inhibition. Although Syn HO-1 and mammalian HO-1 are similar in overall structure and amino acid sequence (57% similarity vs. human HO-1), their molecular surfaces differ in charge distribution. The surfaces of the heme binding sides are both positively charged, but this patch of Syn HO-1 is narrow compared to that of mammalian HO-1. This feature is suited to the selective binding of ferredoxin, the physiological redox partner of Syn HO-1; the molecular size of ferredoxin is approximately 10 kDa whereas the size of NADPH-cytochrome P450 reductase, a reducing partner of mammalian HO-1, is approximately 77 kDa. A docking model of heme-Syn HO-1 and ferredoxin suggests indirect electron transfer from an iron-sulfur cluster in ferredoxin to the heme iron of heme-Syn HO-1.
About this Structure
1WE1 is a Single protein structure of sequence from Synechocystis sp.. Full crystallographic information is available from OCA.
Reference
Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme., Sugishima M, Migita CT, Zhang X, Yoshida T, Fukuyama K, Eur J Biochem. 2004 Nov;271(22):4517-25. PMID:15560792
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