Figure 5.

Alanine scanning mutagenesis of the nsp8 protein. Indicated amino acids were replaced by alanine using site-directed mutagenesis. One micromolar of nsp8 wt and 1 μM of Ala mutants were tested for polymerase activity by measuring [³H]GTP incorporation using a poly(rC) template. Nsp8 polymerase specific activity is represented as follows: empty lozenge (◊); 100% activity relative to nsp8 wt; black lozenge (⧫), between 12 and 40% activity and; asterisk (*), less than 4% activity (see Supplementary Figure 3 for precise values).