Focus on CRISPR tools and therapies
Recent years have seen an acceleration in the number of CRISPR endonucleases available in the bioengineer’s toolbox. Since CRISPR was first turned into an editing tool in 2012, Cas endonucleases have been isolated from many different bacterial species, with different protospacer adjacent motif specificity, activity windows, or guide RNA requirements. Similarly, protein engineering and mutant selection has produced a proliferation of fusions proteins: Cas9 or Cas12a with deaminase for DNA editing; Cas13a with deaminase for RNA base editing; Cas12k with transposase for site-specific DNA integration; and even deactivated Cas9 (dCas9) linked to transcriptional or epigenetic regulators. This minifocus provides an overview of these tools, their use in basic research and provides commentary on progress in turning them into therapeutic modalities.