Table 4.
Mutator effects of proofreading-deficient polAexo mutant in NER-deficient background.a
| lac → lac+ (per 108) | |||||
|---|---|---|---|---|---|
|
lac orientation (strand) |
polA+ | polAexo | polAexo effect | ||
| A. mutL+ strains | |||||
| uvr+ | G·C→A·T | R(lagging) | 0.6 ± 0.3 | 0.5 ± 0.3 | 0.8 |
| L(leading) | 0.8 ± 0.4 | 0.5 ± 0.2 | |||
| G·C→T·A | R(lagging) | 1.0 ± 0.7 | 2.4 ± 1.0 | 2.4 | |
| L(leading) | 1.0 ± 0.4 | 0.9 ± 0.4 | |||
| uvrA | G·C→A·T | R(lagging) | 1.4 ± 0.6 | 1.1 ± 0.9 | 0.8 |
| L(leading) | 1.1 ± 0.4 | 1.3 ± 0.4 | |||
| G·C→T·A | R(lagging) | 1.3 ± 0.6 | 3.3 ± 0.9 | 2.5 | |
| L(leading) | 1.4 ± 0.5 | 1.45 ± 0.6 | |||
| uvrC | G·C→A·T | R(lagging) | 1.2 ± 0.5 | 1.2 ± 0.6 | 1.0 |
| L(leading) | 1.0 ± 0.4 | 1.0 ± 0.5 | |||
| G·C→T·A | R(lagging) | 0.85 ± 0.6 | 2.2 ± 0.5 | 2.6 | |
| L(leading) | 0.86 ± 0.4 | 1.7 ± 1.4 | |||
| B. mutL strains | |||||
| uvr+ | G·C→A·T | R(lagging) | 33 ±15 | 39 ± 20 | 1.2 |
| L(leading) | 139 ± 28 | 153 ± 13 | |||
| G·C→T·A | R(lagging) | 1.4 ± 0.5 | 4.1 ± 1.5 | 2.9 | |
| L(leading) | 4.1 ± 0.9 | 2.8 ± 1.2 | |||
| uvrA | G·C→A·T | R(lagging) | 20 ± 7 | 26 ± 5 | 1.3 |
| L(leading) | 129 ± 18 | 149 ± 16 | |||
| G·C→T·A | R(lagging) | 2.1 ± 0.8 | 4.4 ± 1.2 | 2.1 | |
| L(leading) | 3.2 ± 1.6 | 3.9 ± 1.7 | |||
| uvrC | G·C→A·T | R(lagging) | 21 ± 6 | 37 ± 6 | 1.8 |
| L(leading) | 126 ± 22 | 124 ± 27 | |||
| G·C→T·A | R(lagging) | 2.1 ± 0.6 | 5.8 ± 2.8 | 2.7 | |
| L(leading) | 3.6 ± 0.9 | 3.6 ± 2.0 | |||
a
Mutant frequencies were determined as described in Experimental Procedures. Each entry is based on the median value for 10 independent cultures grown at 37°C. The mismatch-repair-deficient strains were mutL::Tn10. The polAexo effect was calculated dividing the frequency of lac+ mutants in the polAexo and polA+ strains. All polAexo mutator effects shown in bold were statistically significant (P < 0.05, see Experimental procedures).