Pseudophosphorylation of Arabidopsis jasmonate biosynthesis enzyme lipoxygenase 2 via mutation of Ser 600 inhibits enzyme activity.
| Autor: | Kaur D; Department of Plant Science, McGill University, Quebec, Canada; Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Quebec, Canada., Dorion S; Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Quebec, Canada., Jmii S; Département de Chimie, Université du Québec à Montréal, Montréal, Quebec, Canada., Cappadocia L; Département de Chimie, Université du Québec à Montréal, Montréal, Quebec, Canada., Bede JC; Department of Plant Science, McGill University, Quebec, Canada. Electronic address: jacqueline.bede@mcgill.ca., Rivoal J; Institut de Recherche en Biologie Végétale, Université de Montréal, Montréal, Quebec, Canada. Electronic address: jean.rivoal@umontreal.ca. |
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| Jazyk: | angličtina |
| Zdroj: | The Journal of biological chemistry [J Biol Chem] 2023 Mar; Vol. 299 (3), pp. 102898. Date of Electronic Publication: 2023 Jan 10. |
| DOI: | 10.1016/j.jbc.2023.102898 |
| Abstrakt: | Jasmonates are oxylipin phytohormones critical for plant resistance against necrotrophic pathogens and chewing herbivores. An early step in their biosynthesis is catalyzed by non-heme iron lipoxygenases (LOX; EC 1.13.11.12). In Arabidopsis thaliana, phosphorylation of Ser 600 of AtLOX2 was previously reported, but whether phosphorylation regulates AtLOX2 activity is unclear. Here, we characterize the kinetic properties of recombinant WT AtLOX2 (AtLOX2 WT ). AtLOX2 WT displays positive cooperativity with α-linolenic acid (α-LeA, jasmonate precursor), linoleic acid (LA), and arachidonic acid (AA) as substrates. Enzyme velocity with endogenous substrates α-LeA and LA increased with pH. For α-LeA, this increase was accompanied by a decrease in substrate affinity at alkaline pH; thus, the catalytic efficiency for α-LeA was not affected over the pH range tested. Analysis of Ser 600 phosphovariants demonstrated that pseudophosphorylation inhibits enzyme activity. AtLOX2 activity was not detected in phosphomimics Atlox2 S600D and Atlox2 S600M when α-LeA or AA were used as substrates. In contrast, phosphonull mutant Atlox2 S600A exhibited strong activity with all three substrates, α-LeA, LA, and AA. Structural comparison between the AtLOX2 AlphaFold model and a complex between 8R-LOX and a 20C polyunsaturated fatty acid suggests a close proximity between AtLOX2 Ser 600 and the carboxylic acid head group of the polyunsaturated fatty acid. This analysis indicates that Ser 600 is located at a critical position within the AtLOX2 structure and highlights how Ser 600 phosphorylation could affect AtLOX2 catalytic activity. Overall, we propose that AtLOX2 Ser 600 phosphorylation represents a key mechanism for the regulation of AtLOX2 activity and, thus, the jasmonate biosynthesis pathway and plant resistance. Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.) |
| Databáze: | MEDLINE |
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