FIG. 3.
Thermal induction of htpG depends on a σA-dependent promoter. (A) Schematic presentation of htpG-bgaB fusions; the repeats are indicated by arrows; point mutations are written in light gray letters and marked by asterisks. (B) Relative β-galactosidase activities were measured from cultures without temperature shift (light gray columns) and 30 min after a shift from 37 to 50°C (dark gray columns). The enzymatic activity measured with the unstressed strain SS16 was set as one relative BgaB unit (equivalent to a specific activity of 0.012 ± 0.001 U/mg of protein). (C) Northern blot analyses of different fusions as indicated. Total RNA was prepared before (−) and 10 min after (+) a heat shock from 37 to 50°C. Each lane contained 2 μg of total RNA. The bgaB transcript was visualized with DIG-labeled antisense bgaB RNA.