Figure 7. RecA and UmuD₂ may enclose the open active site of DinB.

A–B. In silico modeling of a ternary complex of the proteins. The surface representation of DinB is shown in blue, UmuD₂ in yellow, and RecA in orange. The DNA is relatively enclosed in the complex. C. Statistical covariance of DinB/pol κ residues across evolution. Residues that display statistical covariance with the UmuD₂ binding interface on E. coli DinB define an interface in a similar position on pol κ (shown in red), suggesting a possible rationale for the maintenance of this interface as a site of regulatory protein-protein interactions.