Figure 8.

Five residue loop II mutants exhibit mutator activity in the Trp⁺ reversion assay. The SC18-12 strain containing plasmid encoding either wild-type or loop II mutant were cultured, diluted and plated as described in the Materials and methods section. The bar graph illustrates the increase in reversion frequency of selected loop II mutant over that of wild type. X-axis is the loop II mutant. Y-axis is the increase in reversion frequency over that of wild type. The results are averaged from three independent experiments. Error bars represent the standard deviation.