FIG. 1.
Localization of the regulatory sequence involved in the heat shock regulation of htpG. (A) DNA sequence of the promoter region of htpG. One direct and two inverted repeats are indicated by arrowheads above the DNA sequence; the stop codon of the divergently transcribed yxcA and the putative start codon of htpG are indicated and given in boldface; the −35 and −10 regions of the potential σA-dependent promoter are indicated, given in boldface, and underlined; the transcriptional start site is underlined; the Shine-Dalgarno sequence of htpG is marked by asterisks above the DNA sequence. (B) Schematic representation of different promoter regions transcriptionally fused to the bgaB reporter gene. The repeats are indicated by arrows; the fusions in SS01, SS02, SV02, SV03, and SV09 contain htpG promoter regions (gray rectangles), and SV27 and SV13 contain the promoter of lepA (white rectangles). In strain SV13, part of the downstream region of htpG is fused to the lepA promoter. Asterisks mark the two point mutations. (C) Relative β-galactosidase activities of the transcriptional fusions presented in panel B. The enzymatic activity measured with the unstressed strain SS01 was set as one relative BgaB unit (equivalent to a specific activity of 0.010 ± 0.001 U/mg of protein). The reporter enzyme 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).