FIG. 4.
CtsR negatively regulates hsp gene expression. Expression of the mleA′-bgaB, ctsR′-bgaB, clpX′-bgaB, clpL2′-bgaB, groES′-bgaB, and groESmut′-bgaB (A) and the hsp18′-bgaB, clpP′-bgaB, and grpE′-bgaB (B) transcriptional fusions was measured in the wild-type strain (white and gray bars) or in the ΔctsR mutant (QB4991) (black bars). Cells were grown in LB medium at 37°C. Expression of bgaB fusions was compared in the mid-exponential phase before (white and black bars) or after (gray bars) transfer to 48°C. The numbers indicate induction factors, which were calculated relative to the expression level of each fusion measured in the wild-type strain grown at 37°C.