teRpenE mini bioSynthEtic paTh – Reset
Terpenes represent the largest class of natural compounds with more than 50000 described structures. These molecules are very attractive from an industrial point of view due to their biological activities (artemisinin, taxol, ...), organoleptic properties (menthol, camphor, santalene, germacrene, ...) and physico-chemical characteristics (carotenoids, rubber, …). As natural compounds, the industrial access to terpenes relies still largely on extraction of natural sources such as cultivated plants (mint, camphor, laurel, carrot, hevea...). While this approach is still economically valuable to access quite simple and abundant terpenes such as menthol, camphor or carotene, access to more complex molecules such as artemisinin or taxol is still problematic due to low in planta concentration as well as concerns about sustainable development in relation with biodiversity protection. Although chemical synthesis could offer an interesting clue to this supply problem, the structural complexity of sesqui- and di-terpenes makes chemical synthesis very tedious and prohibitive from an economic point of view. Furthermore the natural characteristic of a chemically synthesized natural product is lost something largely detrimental to some industries. Thus for both regulation, economic and environmental reasons, the industrial access to terpenes has to move from either extraction of natural sources or total chemical synthesis to eco-friendly (bio)-processes.
Terpenes are biosynthesized by virtually all living organisms and their biosynthetic route rely mainly on the supply of pyrophosphate (diphosphate) derivatives of quite simple terpenols such as isopentenol, dimethyallyl alcohol, geraniol, farnesol and geranylgeraniol to transferases and terpene synthases, the enzymes involved in the generation of the various terpene hydrocarbon skeletons. While Nature uses respectively either acetyl-CoA in mevalonate (6 enzymes) or glyceraldehyde-3-P and pyruvate in non-mevalonate (7 enzymes) pathways to synthesize such simple terpenol pyrophosphates, we wonder if a hemi-biosynthetic enzymatic and/or microbial route to terpenoids could be built. This path should avoid the lengthy mevalonate or non-mevalonate pathways, by directly supplying relatively cheap and industrially available terpenols such as isopentenol and dimethyallyl alcohol or naturally available farnesol.
The RESET project thus intends to construct a very short (3 to 4 introduced genes) and totally new in vitro and/or in vivo mini-biosynthetic terpene path, using industrially available C5 alcohols (prenol and isoprenol, > 10000 tons/year) or natural C15 farnesol as substrates. These precursors will be first biocatalytically transformed into their pyrophosphate derivatives, the natural precursors of all terpenes, thanks to two kinases. The formed pyrophosphates will be then transformed thanks to transferases and terpene synthases into terpene hydrocarbons, prenylated aromatics and high molar mass rubber. The genes of all needed enzymes (3 to 4 depending on the targeted final product) are known. The novelty is to use these enzymes in a totally new designed pathway in order to develop a simplified, robust, high yielding and highly valuable industrial bio-access to numerous interesting natural terpenes. As a proof of concept the targeted compounds will be complex terpene hydrocarbons of industrial relevance (santalene, germacrene), an aromatic prenylated compound tryprostatin B and high molar mass rubber. Indeed the project is designed to have the largest possible applicability (i.e. giving access to the largest possible range of prenylated or terpene structures) and being as much as possible in line with sustainable and knowledge-based development as well as with protection and valorization of biodiversity.
Monsieur Gilles Iacazio (Institut des Sciences Moléculaires de Marseille)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Charabot Société Charabot
EMAC Société EMAC
CEA Génoscope Laboratoire de Criblage des Activités de Bioconversions
LCPO Laboratoire de Chimie des Polymères Organiques
iSm2 Institut des Sciences Moléculaires de Marseille
Help of the ANR 611,081 euros
Beginning and duration of the scientific project: September 2014 - 42 Months