Comprehensive profiling of activity and specificity of RNA-guided transposons reveals opportunities to engineer improved variants

A deep mutational scanning study on CRISPR-associated transposon of Scytonema hofmannii (ShCAST). Site-saturation mutagenesis libraries of TnsB, TnsC and TniQ were screened in an E. coli strain engineered to express ccdB toxin gene under arabinose induction. A kanamycin resistance gene was used as a donor DNA. Using activity and specificity screens, we calculated the activity enrichment score and specificity enrichment score for each mutant.