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Saccharomyces cerevisiae is currently one of the most important foreign gene expression systems. S. cerevisiae is an excellent host for high-value metabolite cell factories due to its advantages of simplicity, safety, and nontoxicity. A promoter, as one of the basic elements of gene transcription, plays an important role in regulating gene expression and optimizing metabolic pathways. Promoters control the direction and intensity of transcription, and the application of promoters with different intensities and performances will largely determine the effect of gene expression and ultimately affect the experimental results. Due to its significant role, there have been many studies on promoters for decades. While some studies have explored and analyzed new promoters with different functions, more studies have focused on artificially modifying promoters to meet their own scientific needs. Thus, this article reviews current research on promoter engineering techniques and related natural promoters in S. cerevisiae. First, we introduce the basic structure of promoters and the classification of natural promoters. This section will help in understanding future studies on promoters. The classification of various promoter strategies is then reviewed. In this section, the research of each promoter engineering strategy is divided into static regulation and dynamic regulation respectively. Finally, by grouping related articles together using various strategies, this review anticipates the future development direction of promoter engineering.

Biosensors can be used for high-throughput screening, real-time monitoring of metabolites, and dynamic regulation of metabolic processes, which have been a popular research direction in recent years. Here, five promoters from Saccharomyces cerevisiae were selected to construct Malonyl-CoA sensors with the fapO/fapR system derived from Bacillus subtilis, and pCCW12 was finally selected for further optimization. Based on pCCW12, a series of sensors with different response sensitivities were obtained by selecting different fapO insertion sites and combining the best two or three of them. Then, through a combination of promoter hybrid, intron insertion, and transcription factor modification strategies, we obtained sensors with different effects, one of which, the H-pCCW12(TFBS)-Cti6~fapR sensor, had the lowest background noise, doubled response range and higher response sensitivity compared to the original sensor. Sensors with different characteristics constructed in this study, can be applied to Malonyl-CoA related high-throughput screening and finer regulation of metabolism. It also proves that the combined application of different promoter engineering strategies is a feasible idea for the precise construction and regulation of biosensors.

Objective To produce valerenic acid (VA) in Saccharomyces cerevisiae by engineering a heterologous synthetic pathway.Result Valerena-4,7(11)-diene synthase (VDS) derived from Valeriana officinalis was expressed in S. cerevisiae to generate valerena-4,7(11)-diene as the precursor of VA. By overexpressing the key genes of mevalonate (MVA) pathway ERG8, ERG12 and ERG19 and integrating 4 copies of MBP (maltose binding protein)-VDS-ERG20 gene expression caskets into genome, the production of valerena-4,7(11)-diene was improved to 75 mg/L. On this basis, VA synthases from Lactuca sativa was expressed to produce VA and the most effective VA production strain was used for fermentation, and the yield of VA reached mg/L in the flask and 6.8 mg/L in a 5-L bioreactor fed glucose and ethanol. Conclusions The heterologous synthesis of VA in S. cerevisiae increases the production of VA and provides a reference method for the biosynthesis of other sesquiterpenes.

Objective To produce valerenic acid (VA) in Saccharomyces cerevisiae by engineering a heterologous synthetic pathway.Result 7(11)-diene synthase (VDS) derived from Valeriana o cinalis was expressed in S. cerevisiae to generate valerena-4,7(11)-diene as the precursor of VA. By overexpressing the key genes of mevalonate (MVA) pathway ERG8, ERG12 and ERG19 and integrating 4 copies of MBP (maltose binding protein)-VDS-ERG20 gene expression caskets into genome, the production of valerena-4,7(11)-diene was improved to 75 mg/L. On this basis, VA synthases from Lactuca sativa was expressed to produce VA and the most effective VA production strain was used for fermentation, and the yield of VA reached mg/L in the ask and 6.8 mg/L in a 5-L bioreactor fed glucose and ethanol.Conclusions The heterologous synthesis of VA in S. cerevisiae increases the production of VA and provides a reference method for the biosynthesis of other sesquiterpenes.