Thioredoxin pathway regulated live-cell synthesis of CdSe quantum dots in Saccharomyces cerevisiae

Currently, the application of synthetic biology to artificially manipulate and utilize organisms for the synthesis of desired products such as nanomaterials with excellent fluorescence properties is attracting considerable attention. However, it is still difficult to obtain designed products efficiently due to insufficient knowledge of the biosynthetic mechanisms. The thioredoxin (TRX) and glutathione (GSH) pathways are generally conserved thiol-reductase systems that protect organisms from oxidative stress and are involved in selenium (Se) metabolism. In this study, we revealed the pivotal role of cytoplasmic TRX pathway in regulating the metabolism of Na₂SeO₃ during the live-cell synthesis of cadmium-selenium quantum dots (CdSe QDs) in Saccharomyces cerevisiae by regulating the expression level of genes related to TRX pathway and measuring the intracellular content of selenocysteine (SeCys). The determination of SeCys metabolism in yeast with GSH pathway-related genes deleted demonstrated that the TRX pathway played a more significant role in SeCys metabolism than GSH pathway. A 6.4-fold enhancement in the synthetic yield of CdSe QDs was achieved through the overexpression of TRX pathway-related genes, improvement of synthetic procedure, and supplementation of GSH based on the understanding of biological metabolism. Exploring the mechanism of CdSe QDs live-cell synthesis facilitates the precise manipulation of biological processes for the synthesis of inorganic nanomaterials.