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Partenaires : INRAE BIA​ (Équipes PVPP-BIBS​), BBF – INRAE​  Marseille​, INRAE BioForA, VIB-Boerjan’s group​ ;  Ghent Belgium ​

Coordinateur : Richard Sibout

Personnel BioForA impliqué : Déjardin Annabelle, Pilate Gilles, Laurans Françoise, Belmokhtar Nassim, Boizot Nathalie, Rogier Odile

Autre personnel impliqué: 

Financement : ANR

Budget :

Résumé :

Lignin is a complex phenolic polymer embedded in the polysaccharide matrix of the plant cell wall. Lignin deposition makes plant biomass highly recalcitrant to human use. Surprisingly, both the polymerization of lignin in the plant cell wall and the depolymerization of lignin by microorganisms are carried out by oxidases called laccases. Plant laccases oxidize small phenols synthesized in the cytosol before incorporation into the polymer, while fungal laccases are able to degrade the polymer into smaller oligomers using natural mediators. In both cases, laccase-mediated oxidation generates phenolic radicals of oligolignols that are naturally reactive and tend to re-polymerize. However, in nature, when lignin is oxidized by fungi, re-polymerization from small oligomers is not predominant. This is mainly due to the production of fungal dehydrogenases capable of reducing phenolic radicals. These so-called auxiliary enzymes have a strong affinity for oligosaccharides, which are used as electron acceptors. The DEOX project will compare the activities of plant and fungal laccases and laccase/dehydrogenase pairs to reveal the mechanism of lignin biosynthesis and depolymerization in an oligosaccharide-rich environment. These studies will be carried out in different matrices rich in poly/oligo-saccharide-lignols and lignins naturally grafted with hydroxycinnamic acids. In the course of this project, innovative plant material will be produced: we will express fungal laccases and dehydrogenases in the cell wall of genetically modified plants, with the aim of modifying the structure and lignin content in planta. To understand the differences between fungal and plant laccases, the high-yield production of plant laccases in heterologous expression systems will enable detailed functional characterization and pave the way for structural studies using protein crystallography.
The DEOX project is based on an original consortium of four partners sharing common interests and complementary skills.