FIG 6.

Efficiency of UTP analog incorporation by ZIKV NS5. (A) P/T sequence used to assay UTP analogs. (B) Polymerase reactions were performed in the presence of 10 μM GTP as the first nucleotide and increasing concentrations (in micromolar) of UTP or UTP analogs, as indicated above each lane. The identity of the tested ribonucleotide is indicated at the bottom. The locations of the 20-mer primer and 21- and 22-mer first and second nucleotide extension products are indicated on the right. (C) Quantitative analysis of UTP and UTP analog incorporation. The incorporation efficiency was evaluated on the basis of the extension of 21-mer to 22-mer products. The measured K_1/2 values for UTP, 3′-dUTP, 2′-F-2′-C-Me-UTP, 2′-C-Me-UTP, and 2′-C-ethynyl-UTP were 0.484 μM, 3.376 μM, ~297.6 μM, 25.72 μM, and 2.421 μM, respectively. D_analog values were calculated as K_{1/2, analog}/K_{1/2, UTP} and are shown to the right of the graph.