  RNA-guided gene editing based on the CRISPR-Cas system is currently the most
effective genome editing technique. Here, we report that the SviCas3 from the
subtype I-B-Svi Cas system in Streptomyces virginiae IBL14 is an RNA-guided and
DNA-guided DNA endonuclease suitable for the HDR-directed gene and/or base
editing of eukaryotic cell genomes. The genome editing efficiency of SviCas3
guided by DNA is no less than that of SviCas3 guided by RNA. In particular,
t-DNA, as a template and a guide, does not require a proto-spacer-adjacent
motif, demonstrating that CRISPR, as the basis for crRNA design, is not
required for the SviCas3-mediated gene and base editing. This discovery will
broaden our understanding of enzyme diversity in CRISPR-Cas systems, will
provide important tools for the creation and modification of living things and
the treatment of human genetic diseases, and will usher in a new era of
DNA-guided gene editing and base editing.
