Discovery and characterization of sesquiterpenoid biosynthetic pathways from Basidiomycota

Abstract

Terpenoids are the largest group of secondary metabolites and can be found in organisms ranging from microscopic bacteria to large plant species. These compounds are commonly used for signaling and defense against ecological predators/competitors and possess many unique and interesting biological activities. Many compounds possess enough value that large scale production of terpenoids for biofuel (e.g. farnesene) and pharmaceutical (e.g. artemisinin) applications are well underway. The goal of this work was and still is to uncover the biological machinery responsible for making the bioactive terpenoid compounds. This requires a deep understanding of the underlying biochemistry as well as the genetic organization of the organism from which you are trying to extract said machinery. In the context of this research the biosynthetic machinery is the enzymes (primarily sesquiterpene synthases and P450 monooxygenases) responsible for synthesizing the anticancer illudin terpenoids, and the target organism is the fungus Omphalotus olearius. To accomplish this goal I identified the first biosynthetic pathway enzyme, a protoilludene synthase, and identified putative modifying enzymes that catalyze further modification of the first pathway intermediate. Arguably more importantly, I chose to use our biochemical data to better understand sesquiterpene synthases across many fungal genera. This work provides significant breakthroughs in understanding illudin biosynthesis and also provides a predictive framework for further examination of terpenoid biosynthesis in many different fungal species.