3CLI: Crystal Structure Of Arabidopsis Thaliana Allene Oxide Synthase (Aos, Cytochrome P450 74a, Cyp74a) At 1.80 A Resolution

The oxylipin pathway generates not only prostaglandin-like jasmonates but also green leaf volatiles (GLVs), which confer characteristic aromas to fruits and vegetables. Although allene oxide synthase (AOS) and hydroperoxide lyase are atypical cytochrome P450 family members involved in the synthesis of jasmonates and GLVs, respectively, it is unknown how these enzymes rearrange their hydroperoxide substrates into different products. Here we present the crystal structures of Arabidopsis thaliana AOS, free and in complex with substrate or intermediate analogues. The structures reveal an unusual active site poised to control the reactivity of an epoxyallylic radical and its cation by means of interactions with an aromatic pi-system. Replacing the amino acid involved in these steps by a non-polar residue markedly reduces AOS activity and, unexpectedly, is both necessary and sufficient for converting AOS into a GLV biosynthetic enzyme. Furthermore, by combining our structural data with bioinformatic and biochemical analyses, we have discovered previously unknown hydroperoxide lyase in plant growth-promoting rhizobacteria, AOS in coral, and epoxyalcohol synthase in amphioxus. These results indicate that oxylipin biosynthetic genes were present in the last common ancestor of plants and animals, but were subsequently lost in all metazoan lineages except Placozoa, Cnidaria and Cephalochordata.
PDB ID: 3CLIDownload
MMDB ID: 66165
PDB Deposition Date: 2008/3/19
Updated in MMDB: 2008/12
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 3CLI: monomeric; determined by author and by software (PISA)
Molecular Components in 3CLI
Label Count Molecule
Protein (1 molecule)
Allene Oxide Synthase(Gene symbol: AOS)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB