Fig. 3: Mechanism of DNA loading/melting.
From: Molecular insight into RNA polymerase I promoter recognition and promoter melting
Pol I CC2, Pol I OC intermediate 1, Pol I OC intermediate 2 and Pol I OC2 are depicted from left to right with the rudder (A190 residues 443–455) shown in purple, red, green and orange ribbons. The cryo-EM density for the DNA from 6 Å low-passed filtered maps is shown in the upper panel; zoomed in and rotated views of the upper panel are shown in the lower panel. Initial DNA loading and formation of a small transcription bubble requires clamp closure, while further DNA promoter melting requires clamp opening and insertion of the rudder between the template and non-template strands.
