TABLE 2.

Mutation frequencies for the sodAB fur strains with and without DNA Pol IV and DNA Pol Va

ExptMutation frequency (10−6)
Pol IV+/Pol V+ (YG6176)Pol IV/Pol V+ (YG6179)Pol IV+/Pol V (YG6182)Pol IV/Pol V (YG6127)Pol IV+/Pol V+ (YG6175)Pol IV/Pol V+ (YG6178)Pol IV+/Pol V (YG6181)Pol IV/Pol V (YG6126)
G · C → T · A
    Expt I28.2 ± 3.53.66 ± 0.322.72 ± 0.203.57 ± 0.42
    Expt II35.6 ± 2.52.61 ± 0.122.82 ± 0.153.23 ± 0.30
A · T → C · G
    Expt I12.8 ± 0.612.49 ± 0.183.24 ± 0.252.43 ± 0.15
    Expt II10.0 ± 0.602.08 ± 0.163.7 ± 0.211.86 ± 0.19
    Expt III9.1 ± 0.802.38 ± 0.47
  • a The mutagenicity assay was carried out as described previously (32). Briefly, a single colony was inoculated into 2 ml of M9-glucose minimal medium, and then the overnight culture was diluted 1,000-fold. Eight to twelve diluted cultures were prepared, and they were cultivated overnight. One milliliter of each culture was harvested and washed twice with phosphate buffer (pH 7.4), and then the cell pellet was suspended in phosphate buffer. All of the suspension was spread on one plate for mutation, and a portion of the diluted suspension was used for determining survival. Twenty amino acids were added in the assays (both liquid medium and plates) for growth of sodAB fur strains because the production of amino acids is inhibited by oxygen radicals (3). The values are means ± standard errors.