Cas-SF01, an engineered Cas12i nuclease is an efficient genome editing tool in mammalian cells and plants
The type V-I CRISPR-Cas system is becoming increasingly attractive for its potential utility in gene editing. However, natural nucleases often exhibit low efficiency, limiting their application. Here, we utilized structure-guided rational design and combinatorial protein engineering to optimize an uncharacterized Cas12i nuclease, Cas12i3. Accordingly, we developed Cas-SF01, a Cas12i3 variant that exhibits significantly improved gene-editing activity in mammalian cells and plants. Cas-SF01 displays comparable or superior editing performance compared to SpCas9 or recently engineered Cas12 nucleases. Further analysis of PAM recognition showed that Cas-SF01 has an expanded PAM range and effectively recognizes NTTN and noncanonical NATN and TTVN PAMs. Additionally, we identified an amino acid substitution, D876R, that markedly reduced the off-target effect while maintaining high on-target activity, leading to the development of Cas-SF01HiFi (high-fidelity Cas-SF01). Finally, we demonstrated that Cas-SF01 has robust gene-editing activity in both the monocot plant rice and dicot plant pepper. Our results suggest that Cas-SF01 can serve as a robust gene-editing platform with high efficiency and specificity for future genome editing applications across different organisms. Overall design: to investigate the off-target effect of the Cas12i3 nuclease, we established the GUIDE-Seq experiment of two gene targetes in 293T cell.