Table 2. Growth rates and decoding fidelity of strains expressing wild-type or D2449C rRNA exclusively.
| rRNA mutant | Doubling times (min) | Readthrough and frameshifting levels in lacZ mutants | |||||
| |
30°C |
37°C |
42°C |
p240 |
p415 |
p12-6 |
plac7 |
| Wild-type |
74 ± 4 |
60 ± 2 |
80 ± 6 |
11 ± 1 |
392 ± 27 |
38 ± 3 |
41 ± 7 |
| D2449C | 82 ± 4 | 64 ± 4 | 76 ± 3 | 9 ± 1 | 384 ± 30 | 38 ± 5 | 36 ± 7 |
Growth rates were determined for pKK3535 and pKK2449C-containing derivatives of the Δ7prrn strain, TA542, where all rRNA is plasmid encoded. β-Galactosidase measurements were performed on TA542 derivatives expressing wild-type or D2449C rRNA from plasmids pMO10 and pMO2449C, respectively; lacZ constructs were carried on pBR322-derived plasmids. Values for stop codon readthrough and frameshifting are expressed in Miller units of β-galactosidase (29). All values represent the mean ± SE of three to five independent determinations.