Computational Engineering of the Biosynthesis of the Sand Fly Pheromone Sobralene

Visceral leishmaniasis (VL) is a tropical disease transmitted to humans through the bite of the female sand fly (Lutzomyia longipalpis) which is fatal if untreated and is the second largest parasite killer in the world, after malaria resulting in 20,000-40,000 fatalities per year. Sobralene is a recently discovered sex-aggregation pheromone produced by populations of the sand fly. Sobralene has the potential to be used in pheromone attractant traps as a vector control measure. However, sobralene can only be isolated in very small quantities from the sand flies, and consequently methods need to be developed for its larger scale production. One approach to develop larger scale production is to exploit enzymes to perform key steps in the chemical synthesis. This approach has been successfully applied to the production of closely related molecules such as taxadiene, but its application to the production of sobralene has not been explored. This project will focus on the use of computational methods to inform the design and engineering of an enzyme that can catalyse the synthesis of sobralene from geranyl geranyl pyrophosphate (GGPP). The work will be guided by the close synthetic relationship between sobralene and taxadiene a biosynthetic precurser to the anti-cancer drug Taxol which was co-isolated with sobralene from the sand flies. This suggests that the sobralene synthase will be similar to the taxadiene synthase, providing a starting point for the computational studies. The project will use modern quantum chemical methods such as density functional theory (DFT) to explore the reaction path and transition states for the conversion of GGPP to sobralene. A key component of the project is to understand how the enzyme environment affects the reaction path. The project has no changed from the one originally submitted.