Recent advances in the applications of promoter engineering for the optimization of metabolite biosynthesis.

Cell metabolism in living organisms is largely regulated at the transcriptional level, and the promoters are regarded as basic regulatory elements responsible for transcription initiation. Promoter engineering is an important technique to regulate gene expression and optimize metabolite biosynthesis in metabolic engineering and synthetic biology. The rational and precise control of gene expression in the multi-gene pathways can significantly affect the metabolic flux distribution and maximize the production of specific metabolites. Thus, many efforts have been made to identify natural promoters, construct inducible or hybrid promoters, and design artificial promoters for fine-tuning specific gene expression at the transcriptional level and improving production levels of the metabolites of interest. In this review, we will briefly introduce the architecture and function of both prokaryotic and eukaryotic promoters, and provide an overview of several major approaches for promoter engineering. The recent achievements and advances by promoter engineering for the optimization of metabolite biosynthetic pathways in multiple widely-used model microorganism, including Escherichia coli, Corynebacterium glutamicum and Saccharomyces cerevisiae, will also be extensively discussed.