<i>De novo</i> Biosynthesis of Salvianolic Acid B in <i>Saccharomyces cerevisiae</i> Engineered with the Rosmarinic Acid Biosynthetic Pathway

Abstract

Salvianolic acid B (SAB), also named lithospermic acid B, belongs to a class of water-soluble phenolic acids, originating from plants such as <i>Salvia miltiorrhiza</i>. SAB exhibits a variety of biological activities and has been clinically used to treat cardio- and cerebrovascular diseases and also has great potential as a health care product and medicine for other disorders. However, its biosynthetic pathway has not been completely elucidated. Here, we report the <i>de novo</i> biosynthesis of SAB in <i>Saccharomyces cerevisiae</i> engineered with the heterologous rosmarinic acid (RA) biosynthetic pathway. The created pathway contains seven genes divided into three modules on separate plasmids, pRS424-FjTAL-Sm4CL2, pRS425-SmTAT-SmHPPR or pRS425-SmTAT-CbHPPR, and pRS426-SmRAS-CbCYP-CbCPR. These three modules were cotransformed into <i>S. cerevisiae</i>, resulting in the recombinant strains YW-44 and YW-45. Incubation of the recombinant strains in a basic medium without supplementing any substrates yielded 34 and 30 μg/L of SAB. The findings in this study indicate that the created heterologous RA pathway cooperates with the native metabolism of <i>S. cerevisiae</i> to enable the <i>de novo</i> biosynthesis of SAB. This provides a novel insight into a biosynthesis mechanism of SAB and also lays the foundation for the production of SAB using microbial cell factories.