Metabolic Engineering of Saccharomyces cerevisiae for Production of Shinorine, a Sunscreen Material, from Xylose.

Shinorine, a mycosporine-like amino acid (MAA), is a small molecule sunscreen produced in some bacteria. In this study, by introducing shinorine biosynthetic genes from cyanobacteria Nostoc punctiform into Saccharomyces cerevisiae, we successfully constructed yeast strains capable of producing shinorine. Sedoheptulose 7-phosphate (S7P), an intermediate of the pentose phosphate pathway, is a key substrate for shinorine biosynthesis. To increase the S7P pool, xylose, which is assimilated via the pentose phosphate pathway, was used as a carbon source after introducing xylose assimilation genes from Scheffersomyces stipitis into the shinorine-producing strain. The resulting xylose-fermenting strain produced a trace amount of shinorine when cells were grown in glucose, but shinorine production was dramatically increased by adding xylose in the medium. Shinorine production was further improved by modulating the pentose phosphate pathway through deleting TAL1 and overexpressing STB5 and TKL1. The final engineered strain JHYS17-4 produced 31.0 mg/L (9.62 mg/g DCW) of shinorine in the optimized medium containing 8 g/L of xylose and 12 g/L of glucose, demonstrating that S. cerevisiae is a promising host to produce this natural sunscreen material.