Fig. 4
From: Structural insights into DNA cleavage activation of CRISPR-Cas9 system
The SpCas9-bound topology of the non-target DNA strand (bases −22 to 19). a The EM density (contoured at ~1.0σ) corresponds to the non-target strand from the base-paired PAM proximal end to the connecting region of the PAM distal end to SpCas9 (in hot pink). The possible positions of the PAM distal end are indicated by arrows. For clarity, the HNH domain is not presented in the atomic model (in cartoon). b Top view of the density and possible connecting bases of the PAM distal end to SpCas9. c The EM map (contoured at ~4.0σ) reveals a binding interaction of the PAM proximal end with SpCas9 segment 1151–1156. The fitted atomic model is the crystal structure 4UN3 (Fig. 1c, d). d The bases of the non-target strand that interact with the segment 1151–1156
