Esvelt KM, Mali P, et al. (2013) Orthogonal Cas9 proteins for RNA-guided gene regulation and editing. Nat Methods, Epub ahead of print. doi: 10.1038/nmeth.2681.
Cas9 derived from Streptococcus pyogenes
has been widely used for CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) mediated genome editing. This is due in part to the short NGG sequence requirement of the protospacer adjacent motif (PAM) sequence requirements of S pyogenes
Cas9. The authors of this study use IDT gBlocks® Gene Fragments
to generate human optimized Cas9 orthologs from S thermophilus
, N meningitidis
, and T denticola,
as well as tracRNA expression cassettes for each ortholog. The authors provide new information about the recognition patterns and other characteristics of the Cas9 enzymes. They also demonstrate a possible scenario for use of more than one Cas9, by combining Cas9 orthologs with different PAM requirements to carry out parallel tasks in bacterial and human cell lines.