UCLA

For tens of thousands of years, far preceding recorded human history, mankind has taken advantage of natural products, particularly those in plants for medicinal, cosmetic, and agricultural purposes. In the 21st century that has witnessed scientific advancements in chemical isolation and characterization, we are now capable of commercializing valuable natural products in pure, concentrated form. However, conventional approaches to obtaining such commodity compounds rely on mass destruction of the native producer and extraction-centered procedures that involve heavy use of organic solvents. Relying on these processes as standard methods of natural product sourcing is not sustainable during a time in which environmental conservation is a critical priority for the longevity and well-being of modern society. Though traditional chemical synthesis may seem like a viable alternative to natural sourcing, most of these characterized plant natural products are highly complex with unique stereochemistry that dictates their beneficial bioactivities, proving this approach to be inefficient and plagued by low yields. Monoterpene Indole Alkaloids (MIAs) are a class of plant natural products native to Catharanthus Roseus that encompass thousands of bioactive compounds, many of which have therapeutic value that mitigate lethal diseases such as cancer, Alzheimers, and malaria. Strictosidine is the universal precursor to this therapeutically impactful class of molecules, and thus sustainable, high titer production of this compound is a great stride towards greater accessibility of these sought-after therapeutics. In this dissertation, we report on the development of a de novo yeast strain that can produce 40 mg/L strictosidine. The resulting yeast strain was then demonstrated to be a suitable host for the biosynthesis of heteroyohimbine alkaloids. This strain, specifically, was engineered to synthesize the heteroyohimbine alkaloids, serpentine and alstonine, de novo. We demonstrated that serpentine fluoresces in vivo under blue light and subsequently repurposed this alkaloid as the first small molecule biosensor in yeast for screening applications towards high throughput strain optimization. We accomplished this by collaborating with Professor Dino Di Carlo’s lab to encapsulate strains into microfluidic “PicoShells” to allow growth and propagation of isolated clones during the sorting and post-sort processes and demonstrated effective enrichment of serpentine producing strains among non-producing counterparts.