TABLE 3.
Reversion of nonsense mutation (TAG) in Phe+ mutants accumulating in P. putida wild-type strain and its GO repair-defective derivatives
| Targeta | DNA change | Occurrences (%)
|
Occurrences with rulAB genes inserted into chromosome (%)
|
||||||
|---|---|---|---|---|---|---|---|---|---|
| Wild type | mutM | mutT | mutY | Wild type | mutM | mutT | mutY | ||
| TAG | T → C | 164 (77) | 103 (66) | 14 (8.3) | 24 (12) | 115 (60)c | 59 (63) | 7 (5) | 23 (12) |
| T → G | 19 (9) | 11 (7) | 34 (20) | 5 (2) | 11 (6) | 4 (4.3) | 36 (25) | 5 (2.5) | |
| T → A | 1 (0.5) | 0 | 0 | 0 | 0 | 1 (1.1) | 0 | 0 | |
| G → T | 12 (5.6) | 24 (15.4)b | 1 (0.6) | 176 (85) | 6 (3) | 16 (17.2) | 0 | 168 (84) | |
| A → C | 0 | 3 (2) | 118 (70) | 0 | 4 (2)c | 7 (8)c | 102 (70) | 1 (0.5) | |
| A → G | 13 (6) | 10 (6.4) | 2 (1.1) | 3 (1) | 51 (27)c | 3 (3.2) | 0 | 1 (0.5) | |
| A → T | 4 (1.9) | 5 (3.2) | 0 | 0 | 4 (2) | 3 (3.2) | 0 | 1 (0.5) | |
a
Phe+ mutant colonies used for identification of stationary-phase mutations were picked up on days 3 to 15. Approximately 15 mutants were analyzed per each day. We did not notice remarkable changes in the spectrum of mutations in revertants derived from the earlier or the later period of starvation.
b
Bold type denotes statistically significant differences (P < 0.05) between the mutM and wild-type strains (marked also in bold).
c
Bold type denotes statistically significant differences (P < 0.05) in the presence or absence of rulAB genes (marked also in bold).