CRISPR-mediated protein-tagging signal amplification systems for efficient transcriptional activation and repression in Saccharomyces cerevisiae.

Saccharomyces cerevisiae is an important model eukaryotic microorganism and widely applied in fundamental research and the production of various chemicals. Its ability to efficiently and precisely control the expression of multiple genes is valuable for metabolic engineering. The clustered regularly interspaced short palindromic repeats (CRISPR)-mediated regulation enables complex gene expression programming; however, the regulation efficiency is often limited by the efficiency of pertinent regulators. Here, we developed CRISPR-mediated protein-tagging signal amplification system for simultaneous multiplexed gene activation and repression in S. cerevisiae. By introducing protein scaffolds (SPY and SunTag systems) to recruit multiple copies of regulators to different nuclease-deficient CRISPR proteins and design optimization, our system amplified gene regulation efficiency significantly. The gene activation and repression efficiencies reached as high as 34.9-fold and 95%, respectively, being 3.8- and 8.6-fold higher than those observed on the direct fusion of regulators with nuclease-deficient CRISPR proteins, respectively. We then applied the orthogonal bifunctional CRISPR-mediated transcriptional regulation system to regulate the expression of genes associated with 3-hydroxypropanoic acid production to deduce that CRISPR-associated regulator recruiting systems represent a robust method for simultaneously regulating multiple genes and rewiring metabolic pathways.