tMCK promoter driven Cas9/CRISPR AAV

Cas9 is the nuclease guided by the crRNA and tracrRNA (or trans-activating crRNA) to cleave specific DNA sequences. A guide RNA (gRNA) can be designed to include a hairpin that mimics the tracrRNA-crRNA complex. Binding specificity is based on the gRNA and a three nucleotide NGG sequence called the protospacer adjacent motif (PAM) sequence. With its ease in designing guide sequences to target specific genomic loci, the CRISPR/Cas system is a much simpler, faster, and robust alternative to TALEN and Zinc finger nuclease platforms.

The Cas9 from Streptococcus pyogenes SF370 (SpCas9) is too big to be packaged into AAV for most promoters, and there’s no extra room for including a sgRNA in the same payload with spCas9 in AAV. A small Cas9 from Staphylococcus aureus subsp. aureus (SaCas9) with high efficiency for cleaving mammalian endogenous DNA is the ideal solution to package into AAV along with sgRNA for effective gene modification in vivo.

This is an AAV-DJ (a synthetic serotype made from 8 wild type AAV including AAV2, 4, 5, 8, 9) expressing spCas9 nuclease under a muscle specific tMCK promoter. This AAV-tMCK-saCas9 can be package into other AAV serotypes upon request. This tMCK is composed of a triple tandem copies of mouse MCK enhancer and a ~100bp mouse MCK basal promoter. This promoter shows extremely sensitive tissue-specificity. It’s 15-20 fold stronger than the Enh358MCK promoter and 10-20 fold stronger than the CMV promoter in muscle tissue.

We also offer custom service to package AAV-tMCK-saCas9 with your sgRNA in the same AAV virus. Please contact us for detail.