Genome editing in human cells by Type I-E CRISPR-Cas3

We demonstrate that type I-E CRISPR-Cas3, which is composed of Escherichia coli, mediates distinct DNA cleavage activity in human HEK293T cells. Notably, Cas3 predominantly triggered several thousand base pair deletions upstream of the protospacer adjacent motif (PAM), without prominent off-target activity. These findings suggested that the Class 1 CRISPR system may serve as a novel and unique genome editing tool in eukaryotic cells distinct from the Class 2 CRISPR system.