Directed evolution of CRISPR-Cas9 to increase its specificity.

Lee, Jungjoon K; Jeong, Euihwan; Lee, Joonsun; Jung, Minhee; Shin, Eunji; Kim, Young-Hoon; Lee, Kangin; Jung, Inyoung et al. · Nat Commun · 2018

basic_science · Level V

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Abstract

The use of CRISPR-Cas9 as a therapeutic reagent is hampered by its off-target effects. Although rationally designed S. pyogenes Cas9 (SpCas9) variants that display higher specificities than the wild-type SpCas9 protein are available, these attenuated Cas9 variants are often poorly efficient in human cells. Here, we develop a directed evolution approach in E. coli to obtain Sniper-Cas9, which shows high specificities without killing on-target activities in human cells. Unlike other engineered Cas9 variants, Sniper-Cas9 shows WT-level on-target activities with extended or truncated sgRNAs with further reduced off-target activities and works well in a preassembled ribonucleoprotein (RNP) format to allow DNA-free genome editing.

Medical subject headings