Expanding the CRISPR toolbox by engineering Cas12a orthologs of metagenomic discovery

Cas12a (Cpf1) is a CRISPR-associated nuclease with broad utility in genome editing and molecular diagnostic applications. However, the widespread adoption of CRISPR-Cas12a nucleases and their variants has been hindered by the requirement for a specific protospacer adjacent motif (PAM), relatively low CRISPR RNA (crRNA) activity and the inability to multiplex nucleic acid detection alone. To overcome these limitations, we employed a comprehensive framework combined with AlphaFold2 to de novo mine 1,261 previously unexploited Cas12a orthologs from the global microbiome. Following experimental analysis, we identified the most promising 21 Cas12a nuclease orthologs and designated them “Genie scissor 12” (Gs12). Our analysis uncovered two exceptional variants among these newly identified orthologs: Gs12-10, a first natural PAM-less Cas12a ortholog, which can recognize 52 distinct PAM types, representing a significant 1.8-fold expansion in recognition range compared to the relative LbCas12a PAM; and Gs12-7MAX, an engineered variant of Gs12-7 that exhibited 1.27-fold higher editing efficiency than enAsCas12a-HF. Furthermore, we harnessed Gs12-1, Gs12-4, Gs12-9, and Gs12-18, along with their corresponding engineered crRNAs, to develop a powerful four-channel multiplexed CRISPR-based nucleic acid detection system. The discovery of diverse functions in Cas12a offers a deeper understanding of the CRISPR/Cas12a family. Also, it holds great promise for expanding its applications and uncovering the untapped potential of other CRISPR/Cas systems.