FIGURE 3.

Structure comparisons of the ω subunits of the E. coli and Thermus RNAPs. Shown are close-up views of the ω (gray) and β′ (pink) subunit interactions of the E. coli (a) and Thermus (b) RNAPs. The positions of α helices (E. coli, α₁–α₅; and Thermus, α₁–α₄) of the ω subunits are indicated, and the C termini of the β′ subunits are also indicated.