Fig. 4: Cryo-EM structure of the Pol III transcription complex assembled on the EC scaffold.

a Nucleic acid scaffold used. Bubble position in the EC scaffold is labeled under the sequence. Meanwhile, the positions for the OC and ITC bubbles are also indicated above the sequence (see also Figs. 1a and 3a). The color scheme is the same as in Fig. 1a. The scaffold is opened from −11 to +22. b Cryo-EM reconstruction of the Pol III transcription complex assembled on the EC scaffold. The color scheme is the same as in Fig. 1b. The zoom in panel shows the fitting of the downstream duplex DNA and the presence of the Brf1 ZR domain in the Pol III transcription complex assembled on the EC scaffold. A total of 18 bp of duplex DNA (from +23 to +40) can be fitted in the downstream DNA density in the Pol III transcription complex assembled on the EC scaffold. DNA density is shown as mesh, and protein density for the Brf1 ZR domain is shown as transparent surface. The rest of the Pol III transcription complex assembled on the EC scaffold is shown as transparent ribbon diagram in the background