An efficient KRAB domain for CRISPRi applications in human cells

CRISPRi activities are measured from dCas9 fusions with 57 KRAB domains, which lead to the identification of ZIM3 KRAB-dCas9 fusion as a superior repressor. Clustered regularly interspaced short palindromic repeat interference (CRISPRi), based on the fusion of inactive Cas9 (dCas9) to the Kruppel-associated box (KRAB) repressor, is a powerful platform for silencing gene expression. However, it suffers from incomplete silencing of target genes. We assayed 57 KRAB domains for their repressive potency and identified the ZIM3 KRAB domain as an exceptionally potent repressor. We establish that ZIM3 KRAB-dCas9 fusion silences gene expression more efficiently than existing platforms.