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The channeling of metabolites is an essential step of metabolic regulation in all living organisms. Multifunctional enzymes with defined domains for metabolite compartmentalization are rare, but in many cases, larger assemblies forming multimeric protein complexes operate in defined metabolic shunts. Recently, we described the formation of such a multimeric complex inArabidopsis thaliana. The complex contains a 13-lipoxygenase, allene oxide synthase (AOS), and allene oxide cyclase (AOC). All three plant enzymes are localized in chloroplasts, contributing to the biosynthesis of jasmonic acid (JA). JA and its derivatives act as ubiquitous plant defense regulators in responses to both biotic and abiotic stresses. AOS belongs to the superfamily of cytochrome P450 enzymes and is named CYP74A. Another CYP450 in chloroplasts, hydroperoxide lyase (HPL, CYP74B), competes with AOS for the common substrate. The products of the HPL reaction are green leaf volatiles that are involved in the deterrence of insect pests. Both enzymes represent non-canonical CYP450 family members. AOS and HPL activities are crucial for plants to respond to different biotic foes. The aim of this work was to summarize how plants make use of the LOX2-AOS-AOC2 complex to boost JA biosynthesis over volatile production and how this situation may change in plant communities during mass ingestion by insect pests.
Rustgi, S., Springer, A., Kang, C., von Wettstein, D., Reinbothe, C., Reinbothe, S., Pollmann, S. 2019. ALLENE OXIDE SYNTHASE and HYDROPEROXIDE LYASE, Two Non-Canonical Cytochrome P450s in Arabidopsis thaliana and Their Different Roles in Plant Defense. International Journal of Molecular Sciences 20, 3064. DOI: 10.3390/ijms20123064