The ERC Proof of Concept funded project “Harvesting the Sun” (Acronym SUNLIGHTING) has documented a new environmentally benign approach for synthesis of structurally complex diterpenoids with focus on compounds which can be used as or developed into therapeutics or low calorie natural sweeteners. The production platform is based on the use of photosynthetic cells with sunlight as the energy provider for cell growth and product formation and is based on use of carbon dioxide from the atmosphere as the sole carbon source. In the plant pathway discovery part of the project, it was discovered that several of the pathways are assembled within enzyme complexes organized as dynamic metabolons. A new route to isolation of such metabolons was established. The metabolon involved in forskolin synthesis was found to contain additional factors not directly catalysing steps in the pathway but greatly increasing carbon flux through the pathway by mediating more optimal protein interactions and thereby increasing the yield of forskolin obtained as demonstrated in yeast. An additional patent application has been filed based on identified genes encoding steps in ingenol-3-angelate biosynthesis. To optimize light-/driven production of diterpenoids using photosynthetic cell systems, it was discovered that fusion proteins between the soluble electron donor ferredoxin and the cytochromes P450 resulted in highly channelled transfer of electrons from photosystem I to the cytochrome P450s involved. The forskolin pathway was transferred to the cyanobacterium Synechocystis and the green algae Chlamydomonas. An additional patent application has been filed based on identified genes encoding steps in ingenol-3-angelate biosynthesis. The landscape of diterpenoid structural diversity was expanded dramatically through stereochemically controlled combinatorial biosynthesis using biosynthetic modules from a number of different plant species. The analytical methodology to identify new diterpenoids produced has been optimized by hyphenation. The production platform is designed not to involve the use of genetically modified plants grown in nature. Instead, the platforms are based on photosynthetic cells grown in transparent plastic bags mounted in glass houses to secure environmental containment. Business models for commercial production of forskolin and ingenol-3-angelate as well as addressing the technical aspects of product harvest and isolation have been developed. In the course of the ERC Proof of Concept grant a total of 6 patent applications on diterpenoid building blocks have been filed with inventors being participant researchers from the ERC Proof of Concept project and researchers at our industrial partner Evolva Biotech. The patents are filed with University of Copenhagen as owner and the university has granted an exclusive license to Evolva Biotech to further develop the yeast and photosynthetic production platforms for the focus diterpenoids.
