Figure 2.

Conserved sequence and structural regions of the phiKZ nvRNAP subunits. The second largest (β in bacteria) and the largest (β’ in bacteria) cellular multisubunit RNAPs subunits are shown as arrows in panels A and B, respectively. Evolutionarily conserved sequence regions are labeled according to the Lane and Darst nomenclature: a1-a16 for β and a1-a20 for β’; the size of subunits and the positions of conserved regions are shown for Thermus thermophilus RNAP as a representative bacterial enzyme. Below the β and β’ subunits schemes ihe phiKZ nvRNAP subunits are shown, with sequence regions similar to corresponding msRNAP subunits identified and connected to each other by thin dotted lines. The alignments of conserved regions are presented in Supplementary Figure S1. The DPBB domains that form msRNAP catalytic centers are marked as ovals.