Specific adduction of plant lipid transfer protein by an allene oxide generated by 9-lipoxygenase and allene oxide synthase.
Lipid transfer proteins (LTPs) are ubiquitous plant lipid-binding proteins that have been associated with multiple developmental and stress responses. Although LTPs typically bind fatty acids and fatty acid derivatives in a non-covalent way, studies on the LTPs of barley seeds have identified an abundantly occurring covalently modified form, LTP1b, the lipid ligand of which has resisted clarification. In the present study, this adduct was identified as the alpha-ketol 9-hydroxy-10-oxo-12(Z)-octadecenoic acid. Further studies on the formation of LTP1b demonstrated that the ligand was introduced by nucleophilic attack of the free carboxylate group of the Asp-7 residue of the protein at carbon-9 of the allene oxide fatty acid 9(S),10-epoxy-10,12(Z)-octadecadienoic acid. This reactive oxylipin was produced in barley seeds by oxygenation of linoleic acid by 9-lipoxygenase followed by dehydration of the resulting hydroperoxide by allene oxide synthase. The generation of protein-oxylipin adducts represents a new function for plant allene oxide synthases, enzymes that have earlier been implicated mainly in the biosynthesis of the jasmonate family of plant hormones. Additionally, the LTP-allene oxide synthase interaction opens new perspectives regarding the roles of LTPs in the signaling of plant defense and development.
Bakan
Bénédicte
B
Unité de Recherche Biopolymères Interactions Assemblages, Institut National de la Recherche Agronomique (INRA), Nantes F-44316 Cedex, France. bakan@nantes.inra.fr
Hamberg
Mats
M
Perrocheau
Ludivine
L
Maume
Daniel
D
Rogniaux
Hélène
H
Tranquet
Olivier
O
Rondeau
Corinne
C
Blein
Jean-Pierre
JP
Ponchet
Michel
M
Marion
Didier
D
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D001467:Hordeum; D006825:Hybridomas / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000737:chemistry*; D008024:Ligands; D008084:Lipoxygenase / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008807:Mice, Inbred BALB C; D008956:Models, Chemical; D008958:Models, Molecular; D013379:Substrate Specificity; D013997:Time Factors
D002352:Carrier Proteins; D008024:Ligands; C030363:lipid transfer protein; D008084:Lipoxygenase; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase