A Survey of Genome Editing Activity for 16 Cas12a Orthologs.

The class 2 CRISPR-Cas endonuclease Cas12a (previously known as Cpf1) offers several advantages over Cas9, including the ability to process its own array and the requirement for just a single RNA guide. These attributes make Cas12a promising for many genome engineering applications. To further expand the suite of Cas12a tools available, we tested 16 Cas12a orthologs for activity in eukaryotic cells. Four of these new enzymes demonstrated targeted activity, one of which, from Moraxella bovoculi AAX11_00205 (Mb3Cas12a), exhibited robust indel formation. We also showed that Mb3Cas12a displays some tolerance for a shortened PAM (TTN versus the canonical Cas12a PAM TTTV). The addition of these enzymes to the genome editing toolbox will further expand the utility of this powerful technology.