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. 2007 Dec 21;190(5):1730–1742. doi: 10.1128/JB.01463-07

FIG. 2.

FIG. 2.

Effect of Pol II (ΔpolB and polBex1) and Pol IV (dinB) on the dnaX36 mutator activity. The dinB strains lack both chromosomal and episomal gene copies. All strains are also mismatch repair deficient (mutL). Mutant frequencies were determined as described in Materials and Methods. In this series of experiments, the background mutant frequency for the lac G·C→T·A was higher than in previous experiments (Table 2 and Fig. 1). The present experiments were performed at a later time and under slightly different conditions. Nevertheless, within this series of experiments the results were highly consistent and reproducible over several repeats. (A) Mutant frequencies for lac G·C→T·A transversions. The strains used were: NR13153 (dnaX+), NR13159 (dnaX+ dinB), NR16889 (dnaX+ ΔpolB), NR17225 (dnaX+ ΔpolB dinB), NR16878 (dnaX+ polBex), NR17223 (dnaX+ polBex dinB), NR13256 (dnaX36); NR13274 (dnaX36, dinB); NR16159 (dnaX36, ΔpolB); NR16163 (dnaX36 ΔpolB dinB), NR16108 (dnaX36 polBex), and NR16116 (dnaX36 polBex dinB). The frequencies ± the SE values were 17.2 ± 1.3, 6.3 ± 0.8, 16.8 ± 1.9, 7.9 ± 0.5, 206 ± 13, 119 ± 8, 135 ± 10, 35 ± 5, 643 ± 86, 22 ± 2, 2,210 ± 239, and 1,460 ± 168, respectively. (B) Mutant frequencies for lac A·T→T·A transversions. The strains used were NR16226 (dnaX+), NR16228 (dnaX+ dinB), NR16890 (dnaX+ ΔpolB), NR17226 (dnaX+ ΔpolB dinB), NR16879 (dnaX+ polBex), NR17224 (dnaX+ polBex dinB), NR16246 (dnaX36), NR16248 (dnaX36 dinB), NR16176 (dnaX36 ΔpolB), NR16183 (dnaX36 ΔpolB dinB), NR16169 (dnaX36 polBex), and NR16173 (dnaX36 polBex, dinB). The mutant frequencies ± the SE were 1.1 ± 0.1, 1.1 ± 0.2, 1.6 ± 0.2, 1.7 ± 0.2, 8.3 ± 0.8, 3.8 ± 0.7, 11.9 ± 1.4, 6.9 ± 1.1, 105 ± 14, 6.9 ± 1.2, 263 ± 27, and 189 ± 20, respectively. (C) Mutant frequencies for trpE9777 reversion. Strains used were as described in panel A. The frequencies ± the SE were 313 ± 19, 452 ± 57, 515 ± 28, 289 ± 24, 404 ± 37, 309 ± 19, 3,770 ± 350, 403 ± 49, 9,210 ± 2,268, 633 ± 98, 4,790 ± 487, and 4,280 ± 332, respectively. (D) Mutant frequencies for Rifr. The strains used were as described in panel A. The frequencies ± the SE were 343 ± 35, 374 ± 13, 484 ± 24, 327 ± 19, 500 ± 63, 345 ± 14, 707 ± 48, 617 ± 44, 714 ± 92, 500 ± 71, 3,800 ± 550, and 2,800 ± 218, respectively.