Natural product Biosynthesis and Bioproduction

Big contrats Jennifer!

The alkaloid group focuses its research on the Monoterpene Indole Alkaloids (MIAs), one of the prominent examples of plant specialized metabolites used in our current pharmacopeia. Almost all MIAs derive from the common precursor strictosidine that is further metabolized to yield the plethora of MIAs accumulated in Apocynaceae, Rubiaceae, Nyssaceae, and Loganiaceae. Among MIAs, vinblastine and vincristine, both specific to the Madagascar periwinkle (Catharanthus roseus) are widely exploited in anticancer treatments. The supply of these compounds mostly relies on plant culture and on the extraction of their two precursors, vindoline and catharanthine, from C. roseus leaves, which are further condensed to produce the active compounds.

Figure from Lemos Cruz et al. (2021 ;doi: 10.3390/molecules26123596 ) : Vinblastine and vincristine production via semi-synthetic synthesis.
    (A) Illustration of the semi-synthetic synthesis of vinblastine and vincristine. (B) Tabersonine and catharanthine biosynthesis from strictosidine.
     (C,D) Tabersonine bioconversion in planta (C): by-product vindorosine biosynthesis. (D): vindoline biosynthesis).
                     Solid line: one enzymatic step, discontinuous line: more than one enzymatic step.

Therefore, MIAs supply is obviously highly dependent on plant growth and suffers from recurrent shortages. There‘s a need to develop new strategies to produce these highly molecules. Synthetic biology coupled to metabolic engineering is a valuable solution relying on the transfer of large biosynthetic pathways in heterologous organisms. The resulting bioproduction in microbial cell factories is thus a promising alternative approach to ensure pharmaceutical compound supply. It can be achieved through de novo synthesis or bioconversion of precursors fed to yeast. However, in both cases, it requires the elucidation of the biosynthetic pathways of interest and unfortunately most MIA chemicals do not have their biosynthetic pathways elucidated.
 

Figure adapted from Kulagina et al. (2021 ;https://doi.org/10.1111/1751-7915.13898) 
Tailoring yeast cell factories for vindoline production.
Vindoline biosynthetic pathway and parallell branch vindorosine pathway

• To elucidate or complete the architecture of MIA biosynthesis pathway at molecular and cellular levels in C. roseus but also other MIA producing species as for example Vinca minor.
• To reconstitute pathway in yeast for alkaloid production
• to optimize their production in microbial cell factories to industrial scale
• to identify new enzyme activities to enlarge the chemical diversity through the formation of new-to-nature MIAs through the mix-up of interspecies enzymes in heterologous organisms.