Novel trends for producing plant triterpenoids in yeast

Triterpenoids possess versatile biological activities including antiviral, anticancer, and hepatoprotective activities. They are widely used in medicine and other health-related fields. However, current production of such compounds relies on plant culture and extraction, which brings about concerns for environmental, ecological, and infield problems. With increasing awareness of environmental sustainability, various microbes have been engineered to produce natural products, in which yeast turned out to be feasible for the heterologous biosynthesis of triterpenoids on account of its inherent advantages such as the robustness, safety, and sufficient precursor supplementation. This review has focused on recent progress regarding the biosynthesis of triterpenoids in yeast. The key enzymes to reconstruct the triterpenoid pathways in yeast, include: oxidosqualene cyclases, cytochrome P450s and UDP-glycosyltransferases are systematically presented. We then discuss recent metabolic engineering strategies and future prospects of protein engineering, pathway compartmentalization, product transportation, and other aspects for triterpenoid production in yeast.