CYP77B1 a fatty acid epoxygenase specific to flowering plants. (June 2021)

• Record Type: Journal Article
• Authors: Pineau, Emmanuelle; Sauveplane, Vincent; Grienenberger, Etienne; Bassard, Jean-Etienne; Beisson, Frédéric; Pinot, Franck
• Is Part Of: Plant science. Volume 307(2021)
• Publication Date: 2021-06
• Subjects: Fatty acid -- Epoxide -- Diol -- Cytochrome P450 -- Cutin -- Flower; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2021.110905
• Languages: English
• ISSNs: 0168-9452

Abstract

Highlights: Data mining pointed toward CYP77B1 as a potential fatty acid metabolizing enzyme. In vitro biochemical studies confirmed that CYP77B1 is a fatty acid epoxygenase. RT-qPCR and promoter-driven GUS studies showed highest expression in flower. Flower cutin of loss-of-function mutants cyp77b1 was unchanged compared to wild type. Phylogeny shows gene conservation in flowering plant, suggesting a specific function. Abstract: Contrary to animals, little is known in plants about enzymes able to produce fatty acid epoxides. In our attempt to find and characterize a new fatty acid epoxygenase in Arabidopsis thaliana, data mining brought our attention on CYP77B1. Modification of the N-terminus was necessary to get enzymatic activity after heterologous expression in yeast. The common plant fatty acid C18:2 was converted into the diol 12, 13-dihydroxy-octadec- cis -9-enoic acid when incubated with microsomes of yeast expressing modified CYP77B1 and AtEH1, a soluble epoxide hydrolase. This diol originated from the hydrolysis by AtEH1 of the epoxide 12, 13-epoxy-octadec- cis -9-enoic acid produced by CYP77B1. A spatio-temporal study of CYP77B1 expression performed with RT-qPCR revealed the highest level of transcripts in flower bud while, in open flower, the enzyme was mainly present in pistil. CYP77B1 promoter-driven GUS expression confirmed reporter activities in pistil and also in stamens and petals. In silico co-regulation data led us to hypothesize that CYP77B1 could be involved in cutin synthesis but when flower cutin of loss-of-function mutants cyp77b1 was analyzed, no difference was found compared to cutin of wild type plants. Phylogenetic analysis showed that CYP77B1 is strictly conserved in flowering plants, suggesting a specific function in this lineage.