Fig. 5.

An illustration shows how Cas9 stabilizes the R-loop. In order to construct an R-loop structure, the targeted strand of DNA must link with the 20-nt of gRNA as the DNA curves. The sgRNA not matched to a target DNA sequence (0-nt RNA: DNA) that has a complementary sequence to the gRNA. DNA binding at a sequence matching the 20-nt sgRNA helps proteins accept the RNA–DNA helix and displaced non-target DNA strand. Complete R-loop formation constitutes the signal for the subsequent structure of the targeted gene. gRNA guide RNA, nt nucleotide, sgRNA single-guide RNA, Cas9 CRISPR-associated protein 9, PAM protospacer adjacent motif, Nuc nuclease, Rec recognition