High-throughput analysis of the activities of xCas9, SpCas9-NG and SpCas9 at matched and mismatched target sequences in human cells

xCas9, a recently developed set of Cas9 variants, has been proposed to have the broadest PAM compatibility among CRISPR nucleases as well as robust on-target activity with reduced off-target effects. However, xCas9 activity has been tested at only 20 target sequences in mammalian cells. Here we extensively compared the activities of xCas9 with those of SpCas9 (Cas9 from Streptococcus pyogenes) using a high-throughput approach in human cells.