Fig. 4
From: Non-canonical activation of OmpR drives acid and osmotic stress responses in single bacterial cells
OmpR represses speF to acidify E. coli during osmotic stress. a mRNA levels at pHe 7.2 containing 15% (w/v) sucrose of cadA, cadB, speA, speD, speF, gadA, gadB, and ompF genes were determined by qRT-PCR from wild-type and ompR null strains of E. coli MG1655. Fold expression changes were compared to the wild-type level. The error bars represent the mean ± s.d. (n = 6). The ompR null strain showed increased transcription of speF at high osmolality. b speF mRNA level of an ompR null strain of S. Typhimurium was compared to the wild-type level at pHe 7.2 in the presence of 15% sucrose (w/v). c Representative R488/440 images of wild type, an ompR null strain, an ompR/speF null strain, a speF null strain, and the speF over-expressed strain of E. coli grown at pHe 5.6 or pHe 7.2 in the presence of 15% (w/v) sucrose at the indicated time points. Scale bar, 3 μm. d Plot of the R488/440 ratios of various mutants of E. coli. The complete graph including all strains is in Supplementary Fig. 6. Data set is represented as the mean ± s.e.m. (n = 3). e EMSAs were conducted with biotin end-labeled speF to detect OmpR–speF interaction. Lane 2.1* contained 100-fold excess unlabeled DNA
