2BRJ

X-ray structure of the Allene Oxide Cyclase from Arabidopsis thaliana

2BRJ の概要

• エントリーDOI: 10.2210/pdb2brj/pdb
• 関連するPDBエントリー: 1Z8K
• 分子名称: ARABIDOPSIS THALIANA GENOMIC DNA, CHROMOSOME 3,, GLYCEROL (3 entities in total)
• 機能のキーワード: cyclase, jasmonate synthesis, allene oxide cyclase, beta barrel, isomerase, transit peptide
• 由来する生物種: ARABIDOPSIS THALIANA (MOUSE-EAR CRESS)
• タンパク質・核酸の鎖数: 3
• 化学式量合計: 63437.09

構造登録者

Hofmann, E.,Zerbe, P.,Schaller, F. (登録日: 2005-05-06, 公開日: 2006-08-24, 最終更新日: 2024-11-06)

主引用文献

Hofmann, E.,Zerbe, P.,Schaller, F.
The Crystal Structure of Arabidopsis Thaliana Allene Oxide Cyclase: Insights Into the Oxylipin Cyclization Reaction.
Plant Cell, 18:3201-, 2006

PubMed Abstract: 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.

PubMed: 17085685
DOI: 10.1105/TPC.106.043984

実験手法

X-RAY DIFFRACTION (1.5 Å)