Fig. 1

Performance of basic CRISPR-Cas system: a Overview of schematic CRISPR definition; b Cas proteins are nucleases, endoribonucleases, helicases, or/and integrases: (1) single-strand DNA (break) by nuclease activity; (2) double-strand DNA (break) by nuclease activity; (3) double-strand DNA unwinding by helical activity; c Structure of Cas protein, guide RNA (crRNA) and target DNA complex; d Performance of four-part CRISPR-Cas action mechanism in the prokaryotic cell: 1. Stage—adaptation; 2–3. Stages—expression; 4. Stage—interference