Engineering CRISPR–Cpf1 crRNAs and mRNAs to maximize genome editing efficiency

Cpf1, a type-V CRISPR–Cas effector endonuclease, exhibits gene-editing activity in human cells through a single RNA-guided approach. Here, we report the design and assessment of an array of 42 types of engineered Acidaminococcus sp. Cpf1 (AsCpf1) CRISPR RNA (crRNA) and 5 types of AsCpf1 mRNA in human cell lines. We show that the top-performing modified crRNA (cr3′5F, containing five 2′-fluoro ribose at the 3′ terminus) and AsCpf1 mRNA (full ψ-modification) improved gene-cutting efficiency by, respectively, 127% and 177%, with respect to unmodified crRNA and plasmid-encoding AsCpf1. We also show that the combination of cr3′5F and ψ-modified AsCpf1 or Lachnospiraceae bacterium Cpf1 (LbCpf1) mRNA augmented gene-cutting efficiency by over 300% with respect to the same control, and discovered that 11 out of 16 crRNAs from Cpf1 orthologues enabled genome editing in the presence of AsCpf1. Engineered CRISPR–Cpf1 systems should facilitate a broad range of genome editing applications. An array of chemically engineered CRISPR RNAs and AsCpf1 messenger RNAs leads to improvements in gene-cutting efficiency up to about 300% with respect to unmodified CRISPR RNA and plasmid-encoding AsCpf1.