FIG. 3.

Heat shock represses tra operon transcription in a GroEL-dependent way. Northern blot analyses of traA mRNA levels in E. coli MC4100(R1-16) (wild type [wt]) and NRK117(R1-16) [groEL(Ts)] with (A) and without (C) heat shock. The 23S rRNA is shown as a loading control. (B and D) Quantification of traA signals. The traA signal intensities were normalized against the amount of RNA loaded on the gel, and the intensities of the traA signals in wild-type cells 90 min after heat shock or dilution were set as 1. Data points that are not depicted indicate that traA mRNA was not detectable at these time points. Experiments were repeated twice; one representative result is shown. St, stationary phase at 22°C/37°C.