Project Summary/Abstract
The scalable and sustainable biosynthesis of terpenoid drugs like cyclopamine and diverse libraries of
terpenoid drug candidates will transform the treatment of disease. There are >30,000 unique plant
terpenoids and a valuable subset of these natural products have been approved by the FDA approved or
are currently in clinical trials for cancer treatment, malaria treatment, symptom relief, and immune system
activation. Terpenoids can be biosynthesized in plants through expensive cultivation (i.e., time-, labor-, and
land-intensive), but these approaches can exhibit low and hypervariable yields. Plant terpenoids can also
be produced by chemical total synthesis and semi-synthesis. However, terpenoids can contain many chiral
centers (e.g., 10 in cyclopamine), resulting in complex syntheses with low overall yields. In contrast, the
production of terpenoids in engineered microorganisms is scalable, renewable, and inexpensive, often
producing complex terpenoids from simple sugars and salts. For example, an artemisinic acid-producing
yeast has resulted in 51 million treatments of artemisinin, contributing to the low current cost of artemisinin
anti-malarial combination therapies. This proposal aims to establish methods to accelerate the future
microbial biosynthesis of medicinal terpenoids. The full 30-step biosynthetic pathway for cyclopamine will
be constructed step-by-step in the brewer’s yeast (Saccharomyces cerevisiae) to produce cyclopamine from
simple sugars and salts and solve the challenge of sourcing this drug for the treatment of cancer. In addition,
S. cerevisiae will be engineered to produce sets of new-to-nature triterpenoids through the combinatorial
screening of enzymes with well-characterized activity. The studies will accelerate the microbial biosynthesis
of medicinal terpenoids and diverse libraries of terpenoid drug candidates.