xCas9: Engineering a CRISPR Variant with PAM Flexibility
Type
Blog Post
Published
March 28, 2018, 6:52 p.m.
...SaCas9 with an NNGRRN PAM by mutagenizing the PAM-interacting domain. However, these alternative PAM sequences...often more complex than NGG, resulting in lower overall genome frequency. Despite the progress we’ve made...evolution
Hu et al. used phage-assisted evolution to generate and select for Cas9 mutants with PAM flexibility...catalytically dead SpCas9 (dCas9) fused to the bacterial polymerase subunit ω. This construct is designed to activate...another 72 hours of phage-assisted evolution, generating xCas9 2.0-2.6. This second round of evolution... Cas9 variants with activity on non-NGG PAMs, generating xCas9 3.0-3.13.
To test xCas9 3.0-3.13, Hu et...transcription. Sites containing NG, GAA, or GAT PAMs averaged 56-91% transcriptional activation compared to ...