Rapid production of SaCas9 in plant-based cell-free lysate for activity testing

Cas9 nucleases have become the most versatile tool for genome editing projects in a broad range of organisms. The recombinant production of Cas9 nuclease is desirable for in vitro activity assays or the preparation of ribonucleoproteins (RNPs) for DNA-free genome editing approaches. For the rapid production of Cas9, we explored the use of a recently established cell-free lysate from tobacco (Nicotiana tabacum L.) BY-2 cells. Using this system, the 130-kDa Cas9 nuclease from Staphylococcus aureus (SaCas9) was produced and subsequently purified via affinity chromatography. The purified apoenzyme was supplemented with 10 different sgRNAs, and the nuclease activity was confirmed by the linearization of plasmid DNA containing cloned DNA target sequences.