S67: Engineering terpene synthases with altered product profiles and their use in commercial terpene production in Saccharomyces cerevisiae

Sesquiterpenoids are low abundance secondary metabolites that are commercially attractive for a variety of industries, including flavor and fragrance, crop protection, urban pesticide, pharmaceuticals, and biofuels.  They are chemically complex molecules, typically multicyclic and containing multiple chiral centers.  Their low natural abundance and chemical complexity make them difficult and expensive to extract or synthesize, rendering many of them commercially inaccessible.

Sesquiterpene synthases use farnesyl pyrophosphate (FPP) as their substrate.  The first mechanistic step in catalysis is formation of a carbocation, which then undergoes enzyme specific rearrangements to form an end product or products. During the rearrangement, side reactions often occur giving a mixture of minor products. Protein engineering of these enzymes can result in an altered product profiles, resulting in higher levels of minor products.

S. cerevisiae is a well studied system for production of terpenes. It produces the precursor FPP as part of the ergosterol biosynthetic pathway. Alteration of the key bottleneck enzyme, HMG CoA reductase, and down regulation of squalene synthase results in strains of S. cerevisiae able to produce commercially viable levels of sesquiterpenes in bench, pilot, and commercial scale fermentors. These engineered S. cerevisiae with engineered terpene synthases provide a platform for producing commercial quantities of terpenes that have not been previously available.