TABLE 1.
Mutation frequencies in strain CC105 harboring pBR329-derived plasmids with cloned mutated mutD genesa
| Strain | Mutation frequency (108)
|
|
|---|---|---|
| Rifr | Lac+ | |
| Wild type | 3.8 | 0.9 |
| D12G | 17,664.0 | 713.0 |
| D55G | 8.1 | 0.7 |
| D59G | 6.1 | 0.6 |
| D70G | 10.6 | 4.4 |
| D75G | 5.8 | 3.5 |
| D84G | 3.6 | 1.1 |
| D88G | 4.7 | 0.8 |
| D103G | 4,133.3 | 326.0 |
| D108G | 2.7 | 0.7 |
| D117G | 6.1 | 0.6 |
| D129G | 254.4 | 82.0 |
| D146G | 17.3 | 1.6 |
| D155G | 5.3 | 1.0 |
| D167G | 5,173.3 | 290.4 |
| D219G | 5.1 | 1.0 |
| D230G | 4.1 | 0.9 |
a
Each mutant carries an altered mutD gene, which results in an aspartic acid-to-glycine change at the indicated amino acid position in the ɛ subunit. Between 4 and 10 single colonies of each strain were inoculated into LB medium with tetracycline or ampicillin and grown overnight. Samples were plated on LB medium with rifampin and on lactose minimal plates to measure mutants and on LB medium without rifampin to measure total viable cells. The Lac+ revertants of CC105 strain result from AT→TA transversions (7).