TABLE 7.
Effects of a prfA1 mutation on tryptophan inhibition of translation of the tnaC-UAG-′lacZ construct (at 30°C)
| Strain | Relevant features | Avg β-Gal activity (Miller units) ± SDb
|
+Trp/ −Trpc | |
|---|---|---|---|---|
| −Trp | +Trp | |||
| VK700 | tnaC-UAG-′lacZ | 0.05 | <0.01 | |
| VK700/pGFIBIa | VK700 with su UAG (His) | 274 ± 18 | 173 ± 22 | 0.6 |
| VK701 | VK700 prfA1 | 4 ± 0.8 | 1.5 ± 0.4 | 0.4 |
| VK701/pGFIBIa | VK701 with su UAG (His) | 715 ± 42 | 355 ± 59 | 0.5 |
a
pGFIBI, plasmid carrying a His-inserting tRNAHis UAG suppressor.
b
Cultures were grown at 30°C in minimal medium (49) plus 0.2% glycerol and 0.05% acid-hydrolyzed casein, with (+Trp) or without (−Trp) 100 μg of l-Trp per ml. For β-Gal assay conditions, see Materials and Methods.
c
Ratio of activities with and without Trp.