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Substrate channeling in oxylipin biosynthesis through a protein complex in the plastid envelope ofArabidopsis thaliana
- Source :
- Journal of Experimental Botany
- Publication Year :
- 2018
- Publisher :
- Cold Spring Harbor Laboratory, 2018.
-
Abstract
- Together with the interaction of miR319-regulated TCP transcription factors and the COI1 receptor, the formation of LOX2-AOS-AOC2 complexes controls key steps in jasmonic acid precursor biosynthesis, facilitating fine-tuning of the plant’s defense machinery.<br />Oxygenated membrane fatty acid derivatives termed oxylipins play important roles in plant defense against biotic and abiotic cues. Plants challenged by insect pests, for example, synthesize a blend of different defense compounds that include volatile aldehydes and jasmonic acid (JA), among others. Because all oxylipins are derived from the same pathway, we investigated how their synthesis might be regulated, focusing on two closely related atypical cytochrome P450 enzymes designated CYP74A and CYP74B, respectively, allene oxide synthase (AOS) and hydroperoxide lyase (HPL). These enzymes compete for the same substrate but give rise to different products: the final product of the AOS branch of the oxylipin pathway is JA, while those of the HPL branch comprise volatile aldehydes and alcohols. AOS and HPL are plastid envelope enzymes in Arabidopsis thaliana but accumulate at different locations. Biochemical experiments identified AOS as a constituent of complexes also containing lipoxygenase 2 (LOX2) and allene oxide cyclase (AOC), which catalyze consecutive steps in JA precursor biosynthesis, while excluding the concurrent HPL reaction. Based on published X-ray data, the structure of this complex was modelled and amino acids involved in catalysis and subunit interactions predicted. Genetic studies identified the microRNA 319-regulated clade of TCP (TEOSINTE BRANCHED/CYCLOIDEA/PCF) transcription factor genes and CORONATINE INSENSITIVE 1 (COI1) as controlling JA production through the LOX2-AOS-AOC2 complex. Together, our results define a molecular branch point in oxylipin biosynthesis that allows fine-tuning of the plant’s defense machinery in response to biotic and abiotic stimuli.
- Subjects :
- 0301 basic medicine
0106 biological sciences
allene oxide cyclase
Physiology
Substrate channeling
chloroplast envelope protein complex
Arabidopsis
Allene oxide synthase
Plant Science
01 natural sciences
Mixed Function Oxygenases
Chloroplast Proteins
03 medical and health sciences
chemistry.chemical_compound
Cytochrome P-450 Enzyme System
Biosynthesis
plant defense
Plant defense against herbivory
Arabidopsis thaliana
hydroperoxide lyase
Oxylipins
Plastids
Plastid envelope
030304 developmental biology
0303 health sciences
biology
Arabidopsis Proteins
Jasmonic acid
Allene-oxide cyclase
metabolite channeling
Coronatine
Cell Biology
Oxylipin
biology.organism_classification
Research Papers
lipoxygenase
030104 developmental biology
chemistry
Biochemistry
010606 plant biology & botany
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Botany
- Accession number :
- edsair.doi.dedup.....55bde5a3c5fa7580ecfbc647f7a3d72e