Cross-kingdom expression systems with hybrid promoters in Escherichia coli and Saccharomyces cerevisiae

Abstract

The complexity of biological systems and the genetic diversity of host organisms challenge the ability to port expression systems from one chassis to another. Thus, the genetic elements or biosynthetic pathways have to be reconstructed and optimized with specific promoters for each host, resulting in a tedious construction process. To address these challenges, the redesign of broad-spectrum promoters for cross-species expression across bacteria and eukaryotes is essential. In this study, we successfully developed universal hybrid promoters with variable activity for both Escherichia coli and Saccharomyces cerevisiae. By assembling core promoters with different strengths from S. cerevisiae and E. coli, along with a ribosomal binding site, hybrid broad-spectrum promoters were generated and characterized. To validate our hybrid promoter’s function across both kingdoms, we applied it to a metabolic pathway engineering for the colorant prodeoxyviolacein (PDV) biosynthesis as proof of principle. We observed that our cross-kingdom expression system can produce the PDV across different hosts and confirmed a strong correlation between hybrid promoter strength and PDV production levels across both kingdoms. Together, these universal cross-kingdom gene expression systems enable the redesign of biosynthetic pathways and their expression in diverse microbes simultaneously, unifying the utility of genetic refactoring and quickly identifying productive hosts.