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Title: Structural Insights Into the Evolutionary Paths of Oxylipin Biosynthetic Enzymes

Abstract

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.

Authors:
; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
953078
Report Number(s):
SLAC-REPRINT-2009-206
TRN: US200914%%296
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
Nature 455:363,2008
Additional Journal Information:
Journal Volume: 455
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLENE; AMINO ACIDS; ARABIDOPSIS; AROMATICS; CATIONS; CNIDARIA; CRYSTAL STRUCTURE; CYTOCHROMES; ENZYMES; GENES; LYASES; OXIDES; RADICALS; RESIDUES; SUBSTRATES; SYNTHESIS; Other,OTHER

Citation Formats

Lee, D.-S., Nioche, P., Hamberg, M., and Raman, C.S. Structural Insights Into the Evolutionary Paths of Oxylipin Biosynthetic Enzymes. United States: N. p., 2009. Web.
Lee, D.-S., Nioche, P., Hamberg, M., & Raman, C.S. Structural Insights Into the Evolutionary Paths of Oxylipin Biosynthetic Enzymes. United States.
Lee, D.-S., Nioche, P., Hamberg, M., and Raman, C.S. Wed . "Structural Insights Into the Evolutionary Paths of Oxylipin Biosynthetic Enzymes". United States.
@article{osti_953078,
title = {Structural Insights Into the Evolutionary Paths of Oxylipin Biosynthetic Enzymes},
author = {Lee, D.-S. and Nioche, P. and Hamberg, M. and Raman, C.S.},
abstractNote = {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.},
doi = {},
journal = {Nature 455:363,2008},
number = ,
volume = 455,
place = {United States},
year = {2009},
month = {5}
}