Fig. 2: Target binding leads to large-scale structural arrangements for activation.
From: RNA targeting unleashes indiscriminate nuclease activity of CRISPR–Cas12a2
a, Schematic of crRNA–TS duplex. PFS on target RNA is highlighted. b, Cryo-EM structure of Cas12a2 ternary complex. c, Atomic model of Cas12a2 ternary complex. d, Motion vector map showing conformational changes of Cas12a2 induced following ternary complex formation. Binary complex model shown as grey cartoon. Conformational changes induced by target RNA binding are also shown in Supplementary Video 1. e, Surface electrostatic potential of binary and ternary complex, showing how active site (dotted circle) becomes exposed following ternary complex formation. This is accompanied by the formation of a large positively charged groove adjacent to the activate site. f, Displacement of RuvC gating helix (red) by about 8 Å following ternary complex formation exposes active site residues (light green). g, Target protection revealed by SYBR staining, showing only peripheral cleavage of target RNA when binary complex is in molar excess, and total degradation when target is in excess. The observed protection persisted for 2 h with excess binary complex. Representative of three independent experiments with similar results. For gel source data, see Supplementary Fig. 1. FL, full length.
