JASSY, a chloroplast outer membrane protein required for jasmonate biosynthesis

Abstract

Jasmonates are vital plant hormones that not only act in the stress response to biotic and abiotic influences, such as wounding, pathogen attack, and cold acclimation, but also drive developmental processes in cooperation with other plant hormones. The biogenesis of jasmonates starts in the chloroplast, where several enzymatic steps produce the jasmonate precursor 12-oxophytodienoic acid (OPDA) from α-linolenic acid. OPDA in turn is exported into the cytosol for further conversion into active jasmonates, which subsequently induces the expression of multiple genes in the nucleus. Despite its obvious importance, the export of OPDA across the chloroplast membranes has remained elusive. In this study, we characterized a protein residing in the chloroplast outer membrane, JASSY, which has proven indispensable for the export of OPDA from the chloroplast. We provide evidence that JASSY has channel-like properties and propose that it thereby facilitates OPDA transport. Consequently, a lack of JASSY in Arabidopsis leads to a deficiency in accumulation of jasmonic acids, which results in impaired expression of jasmonate target genes on exposure to various stresses. This results in plants that are more susceptible to pathogen attack and also exhibit defects in cold acclimation. jasmonate | plant hormones | chloroplast | membrane pore | cold acclimation Author contributions: J.S.

Breaking Bad News: Dynamic Molecular Mechanisms of Wound Response in Plants

“…JA biosynthesis begins with release of α-linolenic acid from chloroplast membrane phospholipids, which is then converted into cis-(+)12-oxo-phytodienoic acid (OPDA) through the sequential action of chloroplast-located enzymes, such as the 13-lipoxygenases (13-LOX; Wasternack and Feussner, 2018 ). OPDA is then exported from the chloroplast by JASSY, a protein localized to the outer chloroplast envelope ( Guan et al, 2019 ), and transported into the peroxisomes, presumably by the ABC transporter Comatose (AtABCD1/CTS) and acyl-CoA-binding protein 6 (ACBP6; Theodoulou et al, 2005 ; Ye et al, 2016 ). Once in the peroxisome, OPDA is reduced by OPDA reductases 2 and 3 (OPR2 and OPR3) and subsequently oxidized through two distinct pathways to form JA ( Schaller and Stintzi, 2009 ; Chini et al, 2018 ).…”

Chloroplast-associated molecular patterns as concept for fine-tuned operational retrograde signalling

“…for glycolate, fatty acids (FAX), maltose and other phosphorylated metabolites. Recently a protein named Jassy was identified and suggested to function as oxophytodienoic acid (OPDA) transporter [42]. OPDA is the precursor for jasmonic acid (JA) synthesis in the peroxisome and in addition plays roles in JA-independent signalling [43].…”

Jasmonic Acid at the Crossroads of Plant Immunity and Pseudomonas syringae Virulence

“…Subsequent reactions catalyzed by ALLENE OXIDE SYNTHASE (AOS, a CYTOCHROME P450 CYP74) and ALLENE OXIDE CYCLASE (AOC) generate cyclopentenone OPDA (18 carbons) and dinor-oxo-phytodienoic acid (dnOPDA, a 16-carbon homolog of OPDA) ( Figure 1 a). The OPDA is then exported from chloroplasts by JASSY (a membrane channel that is located in the outer envelope of chloroplasts) [ 13 ] and imported into peroxisomes by COMATOSE (CTS), an ABC transporter located in the peroxisome membrane [ 14 ]. Subsequently, OPDA REDUCTASE 3 (OPR3) converts OPDA to 3-oxo-2(2′[Z]-pentenyl)-cyclopentane-1-octanoic acid (OPC8), which in turn, undergoes three consecutive reactions of β-oxidation catalyzed by ACYL-CoA-OXIDASE 1 (ACX1) to produce JA ( Figure 1 a).…”

“…These enzymes convert α-linolenic acid into OPDA through a series of reactions. OPDA is then exported from the CPs by the JASSY transmembrane protein present on the inner membrane of the CPs [ 13 ]. OPDA enters into PRs through an ABC transporter membrane protein known as COMATOSE (CTS) [ 14 ].…”