Identification and characterization of phlorizin transporter from Arabidopsis thaliana and its application for phlorizin production in Saccharomyces cerevisiae

Bioengineering aimed at producing complex and valuable plant specialized metabolites in microbial hosts requires efficient uptake of precursor molecules and export of final products to alleviate toxicity and feedback inhibition. Plant genomes encode a vast repository of transporters of specialized metabolites that-- due to lack of molecular knowledge--remains largely unexplored in bioengineering. Using phlorizin as a case study--an anti-diabetic and anti-cancerous flavonoid from apple--we demonstrate that brute-force functional screening of plant transporter libraries in Xenopus oocytes is a viable approach to identify transporters for bioengineering. By screening 600 Arabidopsis transporters, we identified and characterized purine permease 8 (AtPUP8) as a bidirectional phlorizin transporter. Functional expression in the plasma membrane of a phlorizin-producing yeast strain increased phlorizin titer by more than 80 %. This study provides a generic approach for identifying plant exporters of specialized metabolites and demonstrates the potential of transport-engineering for improving yield in bioengineering approaches.