(A) Close-up view of the HNH domain within the wild-type (WT) full-length Cas9, showing seven communities of synchronized dynamics, indicated using different colors. Three communities are allosteric (A1 yellow, A2 cyan, and A3 purple), since they hold most of the residues that compose the allosteric pathway (shown as spheres). The non-allosteric communities (NA1 orange, NA2 tan, NA3 red, NA4 black) include only a few allosteric residues. (B) Circular networks reporting the mutation-induced edge betweenness change (ΔEB), a measure of communication gain or loss between couples of communities upon mutation. For each of the K855A, K810A, and K848A mutants, the HNH communities are displayed in a circle and are connected by links with thickness proportional to ΔEB (border sizes also correspond to the ΔEB of the specific community). Negative ΔEB (red) represents loss of communication, positive ΔEB (blue) indicates communication gain upon mutation (Figure 4—figure supplement 1).