Biomanufacturing allows us to reduce our dependence on fossil fuels by leveraging cells to synthesize chemicals typically derived from fossil fuels. Microbial cells like yeast require a sugar feedstock to grow and proliferate, and agricultural biomass is an attractive renewable resource for fermentation sugars. However, using agricultural biomass for biomanufacturing requires sugars to be liberated from lignocellulosic biomass (plants) through the action of targeted enzymes. Separately, it is challenging to engineer engineering yeast that can efficiently utilize both hexose and pentose sugars derived from lignocellulose. To ensure co-utilization of these sugars, one must engineer transporter proteins on the surface of cells, as these proteins control the molecules that move across a cell’s membrane. A sugar transporter family, Sugars Will Eventually be Exported Transporter (SWEET) family, is abundant in plants but was recently discovered in early-branching anaerobic fungi. Several SWEETs were bioinformatically identified in anaerobic fungal strains and screened for function in sugar transporter-deficient strains of <i>S. cerevisiae</i>. The transporter NcSWEET1 demonstrated co-utilization of glucose and xylose, which is an attractive trait for metabolic engineering to enable growth on lignocellulosic hydrolysates. The strain performance of engineered yeast improved through forming transporter chimeras with other SWEETs. To maximize the transporters’ translational potential for biomanufacturing, we are currently determining whether recombinant expression of SWEETs induces yeast cell stress responses. Fluorescent reporters have been developed to determine the activity levels of the unfolded protein response (UPR) due to recombinant SWEET expression. Overall, this work provides a roadmap for screening and engineering SWEET transporters from anaerobic fungi in yeast to increase their transport capabilities for biomanufacturing.

Sweet proteins: Engineering sugar transporters for biomanufacturing

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.