Figure 4
The artiodactyl A3 proteins catalyze DNA cytosine deamination. (A) Cow A3Z2 triggers a strong mutator phenotype in E. coli. RifR mutation frequency of 4–6 independent bacteria cultures expressing basal levels of indicated A3 proteins (each X represents data from a single culture). To facilitate comparisons, the median mutation frequency is indicated for each condition. (B) Cow A3Z3 triggers a modest mutator phenotype in E. coli. Labels and conditions are similar to those in panel (A), except IPTG was used to induce protein expression. (C) Non-induced cow A3Z1 triggers a strong mutator phenotype in E. coli, which is completely abrogated by substituting the catalytic glutamate (E58) for alanine. Labels are similar to those in panel (A).