The study focuses on creating a library of yeast strains that exhibit estrogen-dependent growth regulation, using a combination of CRISPR-Cas9 gene editing and protein fusion techniques. The authors created a library of 775 strains, each containing a different essential gene fused to the estrogen receptor (ERdd) and a green fluorescent protein (GFP) marker. The strains were screened for their ability to grow in response to estradiol, a synthetic estrogen mimic. The primary screening was performed on agar plates, followed by a secondary screening in liquid culture. The top 46 strains were selected for further analysis, including proteome and metabolome analysis.
The study also explored the stability and competitiveness of the ERdd strains, as well as their potential for gene editing and containment. The results show that the ERdd strains exhibit significant changes in protein abundance and metabolite levels in response to estradiol, and that they are able to outcompete the parent strain in growth assays. The study highlights the potential of the ERdd system for the precise control of gene expression in yeast and its applications in biotechnology and synthetic biology.