2gin: Difference between revisions
New page: left|200px<br /><applet load="2gin" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gin, resolution 1.800Å" /> '''X-ray structure of ... |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:2gin.gif|left|200px]]<br /><applet load="2gin" size=" | [[Image:2gin.gif|left|200px]]<br /><applet load="2gin" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="2gin, resolution 1.800Å" /> | caption="2gin, resolution 1.800Å" /> | ||
'''X-ray structure of the wt allene oxide cyclase 2 from arabidopsis thaliana'''<br /> | '''X-ray structure of the wt allene oxide cyclase 2 from arabidopsis thaliana'''<br /> | ||
==Overview== | ==Overview== | ||
We describe the crystallization and structure elucidation of Arabidopsis | We describe the crystallization and structure elucidation of Arabidopsis thaliana allene oxide cyclase 2 (AOC2), a key enzyme in the biosynthesis of jasmonates. In a coupled reaction with allene oxide synthase, AOC2 releases the first cyclic and biologically active metabolite, 12-oxo-phytodienoic acid (OPDA). AOC2 (AT3G25770) folds into an eight-stranded antiparallel beta-barrel with a C-terminal partial helical extension. The protein forms a hydrophobic binding cavity with two distinct polar patches. AOC2 is trimeric in crystals, in vitro and in planta. Based on the observed folding pattern, we assigned AOC2 as a low molecular weight member of the lipocalin family with enzymatic activity in plants. We determined the binding position of the competitive inhibitor vernolic acid (a substrate analog) in the binding pocket. Based on models for bound substrate 12,13-epoxy-9,11,15-octadecatrienoic acid and product OPDA, we propose a reaction scheme that explains the influence of the C15 double bond on reactivity. Reaction is promoted by anchimeric assistance through a conserved Glu residue. The transition state with a pentadienyl carbocation and an oxyanion is stabilized by a strongly bound water molecule and favorable pi-pi interactions with aromatic residues in the cavity. Stereoselectivity results from steric restrictions to the necessary substrate isomerizations imposed by the protein. | ||
==About this Structure== | ==About this Structure== | ||
2GIN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana] with NA and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Allene-oxide_cyclase Allene-oxide cyclase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.99.6 5.3.99.6] Full crystallographic information is available from [http:// | 2GIN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana] with <scene name='pdbligand=NA:'>NA</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Allene-oxide_cyclase Allene-oxide cyclase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.99.6 5.3.99.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GIN OCA]. | ||
==Reference== | ==Reference== | ||
| Line 21: | Line 21: | ||
[[Category: beta barrel]] | [[Category: beta barrel]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:32:02 2008'' | ||
Revision as of 18:32, 21 February 2008
|
X-ray structure of the wt allene oxide cyclase 2 from arabidopsis thaliana
OverviewOverview
We describe the crystallization and structure elucidation of Arabidopsis thaliana allene oxide cyclase 2 (AOC2), a key enzyme in the biosynthesis of jasmonates. In a coupled reaction with allene oxide synthase, AOC2 releases the first cyclic and biologically active metabolite, 12-oxo-phytodienoic acid (OPDA). AOC2 (AT3G25770) folds into an eight-stranded antiparallel beta-barrel with a C-terminal partial helical extension. The protein forms a hydrophobic binding cavity with two distinct polar patches. AOC2 is trimeric in crystals, in vitro and in planta. Based on the observed folding pattern, we assigned AOC2 as a low molecular weight member of the lipocalin family with enzymatic activity in plants. We determined the binding position of the competitive inhibitor vernolic acid (a substrate analog) in the binding pocket. Based on models for bound substrate 12,13-epoxy-9,11,15-octadecatrienoic acid and product OPDA, we propose a reaction scheme that explains the influence of the C15 double bond on reactivity. Reaction is promoted by anchimeric assistance through a conserved Glu residue. The transition state with a pentadienyl carbocation and an oxyanion is stabilized by a strongly bound water molecule and favorable pi-pi interactions with aromatic residues in the cavity. Stereoselectivity results from steric restrictions to the necessary substrate isomerizations imposed by the protein.
About this StructureAbout this Structure
2GIN is a Single protein structure of sequence from Arabidopsis thaliana with and as ligands. Active as Allene-oxide cyclase, with EC number 5.3.99.6 Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of Arabidopsis thaliana allene oxide cyclase: insights into the oxylipin cyclization reaction., Hofmann E, Zerbe P, Schaller F, Plant Cell. 2006 Nov;18(11):3201-17. Epub 2006 Nov 3. PMID:17085685
Page seeded by OCA on Thu Feb 21 17:32:02 2008