The amidohydrolases IAR3 and ILL6 contribute to jasmonoyl-isoleucine hormone turnover and generate 12-hydroxyjasmonic acid upon wounding in Arabidopsis leaves.
Jasmonates (JAs) are a class of signaling compounds that mediate complex developmental and adaptative responses in plants. JAs derive from jasmonic acid (JA) through various enzymatic modifications, including conjugation to amino acids or oxidation, yielding an array of derivatives. The main hormonal signal, jasmonoyl-L-isoleucine (JA-Ile), has been found recently to undergo catabolic inactivation by cytochrome P450-mediated oxidation. We characterize here two amidohydrolases, IAR3 and ILL6, that define a second pathway for JA-Ile turnover during the wound response in Arabidopsis leaves. Biochemical and genetic evidence indicates that these two enzymes cleave the JA-Ile signal, but act also on the 12OH-JA-Ile conjugate. We also show that unexpectedly, the abundant accumulation of tuberonic acid (12OH-JA) after wounding originates partly through a sequential pathway involving (i) conjugation of JA to Ile, (ii) oxidation of the JA-Ile conjugate, and (iii) cleavage under the action of the amidohydrolases. The coordinated actions of oxidative and hydrolytic branches in the jasmonate pathway highlight novel mechanisms of JA-Ile hormone turnover and redefine the dynamic metabolic grid of jasmonate conversion in the wound response.
From the Institut de Biologie Moléculaire des Plantes, Unité Propre de Recherche 2357 du Centre National de la Recherche Scientifique, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France.
Emilie
E
Widemann
Laurence
L
Miesch
Raphaël
R
Lugan
Emilie
E
Holder
Clément
C
Heinrich
Yann
Y
Aubert
Michel
M
Miesch
Franck
F
Pinot
Thierry
T
Heitz
D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D007532:Isoleucine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D054883:Oxylipins / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology* / Q000235:genetics
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; C011006:jasmonic acid; D000581:Amidohydrolases; C000612601:ILL6 protein, Arabidopsis; C118815:IAR3 protein, Arabidopsis
Arabidopsis; Conjugate; Enzymes; Hormone Catabolism; Hydrolases; Jasmonate Metabolism; Phytohormones; Plant Defense; Wound Response