Developing synthetic hybrid promoters to increase constitutive or diauxic shift-induced expression in Saccharomyces cerevisiae

Fine-tuning of the expression of genes is crucial for cell factory construction. Promoters are the most important tools to control gene expression. However, native promoters are often limited by their transcriptional ability. In this study, we sought to overcome the limitations of native promoters in Saccharomyces cerevisiae through the construction of hybrid promoter libraries for both constitutive promoters and promoters induced by diauxic shift. A series of hybrid constitutive promoters were constructed by combing the upstream activation sequences and changing the core promoter elements. The transcriptional capacity of the strongest promoter was 2-fold higher than that of the yeast native TEF1 promoter. Aside from the constitutive promoters, hybrid promoters that were induced in the post-diauxic phase were also constructed. These promoters had low transcriptional ability during growth on glucose and automatically activated upon growth with a diauxic shift. The strength of these promoters was also increased by replacing the core promoter with strong core promoters. Our study provides a series of constitutive and diauxic shift-induced promoters with a broad range of transcriptional capacity and will facilitate synthetic biology and metabolic engineering application.