Skip to main content
. 2021 Dec 16;9:786354. doi: 10.3389/fchem.2021.786354

FIGURE 1.

FIGURE 1

The structure of CRISPR-Cas9 system. (A) Basic structure domains of Cas9. Cas9 contains five different domains, RuvC domain, BH domain, REC domain, HNH domain, and PI domain, which are divided into nuclease (NUC) lobe and recognition (REC) lobe. (B) Crystal structures of CRISPR-Cas9. The HNH, RuvC, and PI domains reside in the Cas9 NUC lobe. The REC lobe of Cas9 contains other regions that interact with the sgRNA–DNA duplex. The HNH nuclease domain is responsible for slicing the complementary DNA strand of sgRNA, while the RuvC domain is responsible for slicing the other strand. Domains with conformational changes are indicated by dashed lines (reproduced from (Guo et al., 2019) with permission from Cell research). (C) Schematic of the sgRNA–target DNA complex-(N-any nucleotide), and three-dimensional structure of sgRNA. The target DNA shows in blue, PAM is labeled by green. The orange color shows the sequence and structure of sgRNA, which contains three stem loops (reproduced from (Anders et al., 2014) with permission from Nature).