Fig. 2 |. Cryo-EM structures of the Cas9 interrogation complex, compared to previously determined crystal structures.
a, Unsharpened cryo-EM map (threshold 4σ) of Cas9 interrogation complex in open-protein/linear-DNA conformation, alongside apo Cas9 crystal structure (PDB 4CMP, 2Fo-Fc, threshold 1.5σ). b, Closed-protein/bent-DNA conformation (threshold 5σ), alongside Cas9:sgRNA crystal structure (PDB 4ZT0, 2Fo-Fc, threshold 1.5σ). Green, NUC lobe; blue, REC lobe domains 1/2; light blue, REC lobe domain 3; orange, guide RNA; magenta, DNA. Maps produced in the present work are displayed with full opacity. REC lobe domain 3 does not appear in the cryo-EM structure in a (see Supplementary Information). Additional classes observed in the closed-protein state are shown in Extended Data Fig. 3a.