Optimization of the CRISPR/Cas9 system using adh1 promoter derivatives in fission yeast

The CRSIPR/Cas9 system has been applied to fission yeast, but there remain some rooms for improvement. Here we report that the weaker versions of the adh1 ⁺ promoter, adh11 and adh41 promoters, for the potentially cytotoxic Cas9 achieved highly efficient mutagenesis and gene deletion at the ade6 ⁺ locus. Employing a drug-selectable marker instead of conventional auxotrophic markers, our new vector system is compatible with a variety of experimental settings including prototrophic/auxotrophic strains and complete/minimal media.