CRISPR/Cas9 System: A Bacterial Tailor for Genomic Engineering

Figure 2

An overview of CRISPR/Cas9 mediated genome editing. The sgRNA that comprises a single strand RNA guides the Cas9 protein to the target DNA site with a sequence complementary to the 5′ end of sgRNA. The PAM dependent recognition of target DNA sequence by Cas9 initiates the DNA cleavage at a specific site 3 bp upstream of the PAM. The double-strand break generated by Cas9 can be repaired by either NHEJ or HDR. The NHEJ repair often results in indel mutation and inactivation of the gene while the HDR allows the high-fidelity precise genome editing when supplied with donor template.