Proteomics analysis of a new Cas9-targeting PROTAC molecule

Scientists have developed several methods to control the activity of Cas protein in a timely way and hence reduce off-target effects, including anti-CRISPR proteins and small molecule inhibitors. The PROTAC is a new conception of using the natural ubiquitin-proteasome system to degrade the protein of interest in drug design and development. Here, we engineered Cas proteins (Cas9, Cas12, and Cas13) by inserting a Phe-Cys-Pro-Phe (FCPF) amino acid sequence (also known as the π-clamp system) and demonstrate that the modified CasFCPF proteins could be labeled in live cells by perfluoroaromatics carrying FITC fluorophore or were degraded by perfluoroaromatics-functionalized PROTAC (PROTAC-FCPF). Proteome-wide analysis of PROTAC-FCPF-mediated Cas9FCPF protein degradation revealed high target specificity, suggesting a wide application of chemically induced proximity in combination with site-specific protein modification in the regulation of protein stability, activity and functionality.