Figure 2.

Transcription properties of the mosaic RNAP variants. (A) Positions of the β′ substitutions in mosaic RNAPs shown on the structure of Tth TEC in complex with Stl (2PPB²). RNAP orientation corresponds to Figure 1A. The β (pink), β′ (green), α (blue) and ω (gray) subunits are shown as ribbons; the FL and the jaw-domain are in red and turquoise, respectively. (B) Rates of single nucleotide addition by mosaic Taq TECs assembled on the minimal scaffold (top) were measured at 20°C and 1 mM NTP as described previously.¹⁸ Numbers in bold indicate fold differences in comparison with wild-type Taq RNAP. (C) Thermostability of mosaic Taq RNAPs. RNAPs were incubated for 3 min at indicated temperatures and their activity was measured on the T7A1 promoter in the presence of a CpA primer and UTP (10 µM each) for 5 min at 55°C.