2iag
From Proteopedia
(New page: 200px<br /> <applet load="2iag" size="450" color="white" frame="true" align="right" spinBox="true" caption="2iag, resolution 2.15Å" /> '''Crystal structure o...) |
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| - | [[Image:2iag.gif|left|200px]]<br /> | + | [[Image:2iag.gif|left|200px]]<br /><applet load="2iag" size="350" color="white" frame="true" align="right" spinBox="true" |
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caption="2iag, resolution 2.15Å" /> | caption="2iag, resolution 2.15Å" /> | ||
'''Crystal structure of human prostacyclin synthase'''<br /> | '''Crystal structure of human prostacyclin synthase'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Prostacyclin synthase (PGIS) catalyzes an isomerization of prostaglandin | + | Prostacyclin synthase (PGIS) catalyzes an isomerization of prostaglandin H(2) to prostacyclin, a potent mediator of vasodilation and anti-platelet aggregation. Here, we report the crystal structure of human PGIS at 2.15 A resolution, which represents the first three-dimensional structure of a class III cytochrome P450. While notable sequence divergence has been recognized between PGIS and other P450s, PGIS exhibits the typical triangular prism-shaped P450 fold with only moderate structural differences. The conserved acid-alcohol pair in the I helix of P450s is replaced by residues G286 and N287 in PGIS, but the distinctive disruption of the I helix and the presence of a nearby water channel remain conserved. The side-chain of N287 appears to be positioned to facilitate the endoperoxide bond cleavage, suggesting a functional conservation of this residue in O-O bond cleavage. A combination of bent I helix and tilted B' helix creates a channel extending from the heme distal pocket, which seemingly allows binding of various ligands; however, residue W282, placed in this channel at a distance of 8.4 A from the iron with its indole side-chain lying parallel with the porphyrin plane, may serve as a threshold to exclude most ligands from binding. Additionally, a long "meander" region protruding from the protein surface may impede electron transfer. Although the primary sequence of the PGIS cysteine ligand loop diverges significantly from the consensus, conserved tertiary structure and hydrogen bonding pattern are observed for this region. The substrate-binding model was constructed and the structural basis for prostacyclin biosynthesis is discussed. |
==Disease== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 2IAG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with NA and HEM as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Prostaglandin-I_synthase Prostaglandin-I synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.99.4 5.3.99.4] Full crystallographic information is available from [http:// | + | 2IAG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=NA:'>NA</scene> and <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Prostaglandin-I_synthase Prostaglandin-I synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.99.4 5.3.99.4] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IAG OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Prostaglandin-I synthase]] | [[Category: Prostaglandin-I synthase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Chan, N | + | [[Category: Chan, N L.]] |
| - | [[Category: Chiang, C | + | [[Category: Chiang, C W.]] |
| - | [[Category: Wang, L | + | [[Category: Wang, L H.]] |
| - | [[Category: Yeh, H | + | [[Category: Yeh, H C.]] |
[[Category: HEM]] | [[Category: HEM]] | ||
[[Category: NA]] | [[Category: NA]] | ||
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[[Category: prostacyclin synthase]] | [[Category: prostacyclin synthase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:50:36 2008'' |
Revision as of 15:50, 21 February 2008
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Crystal structure of human prostacyclin synthase
Contents |
Overview
Prostacyclin synthase (PGIS) catalyzes an isomerization of prostaglandin H(2) to prostacyclin, a potent mediator of vasodilation and anti-platelet aggregation. Here, we report the crystal structure of human PGIS at 2.15 A resolution, which represents the first three-dimensional structure of a class III cytochrome P450. While notable sequence divergence has been recognized between PGIS and other P450s, PGIS exhibits the typical triangular prism-shaped P450 fold with only moderate structural differences. The conserved acid-alcohol pair in the I helix of P450s is replaced by residues G286 and N287 in PGIS, but the distinctive disruption of the I helix and the presence of a nearby water channel remain conserved. The side-chain of N287 appears to be positioned to facilitate the endoperoxide bond cleavage, suggesting a functional conservation of this residue in O-O bond cleavage. A combination of bent I helix and tilted B' helix creates a channel extending from the heme distal pocket, which seemingly allows binding of various ligands; however, residue W282, placed in this channel at a distance of 8.4 A from the iron with its indole side-chain lying parallel with the porphyrin plane, may serve as a threshold to exclude most ligands from binding. Additionally, a long "meander" region protruding from the protein surface may impede electron transfer. Although the primary sequence of the PGIS cysteine ligand loop diverges significantly from the consensus, conserved tertiary structure and hydrogen bonding pattern are observed for this region. The substrate-binding model was constructed and the structural basis for prostacyclin biosynthesis is discussed.
Disease
Known diseases associated with this structure: Hypertension, essential OMIM:[601699]
About this Structure
2IAG is a Single protein structure of sequence from Homo sapiens with and as ligands. Active as Prostaglandin-I synthase, with EC number 5.3.99.4 Full crystallographic information is available from OCA.
Reference
Crystal structure of the human prostacyclin synthase., Chiang CW, Yeh HC, Wang LH, Chan NL, J Mol Biol. 2006 Dec 1;364(3):266-74. Epub 2006 Sep 20. PMID:17020766
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