Figure 1From: A new suite of tnaA mutants suggests that Escherichia coli tryptophanase is regulated by intracellular sequestration and by occlusion of its active site Indole is produced when TnaA becomes diffuse. E. coli cells (GL619) expressing TnaA-sfGFP from the constitutive tufA promoter were grown in M9 minimal medium supplemented with 1% casamino acids and 0.5 mM tryptophan. A. Cell growth (OD600). B. TnaA-sfGFP localization at different times. GFP fluorescence and phase contrast images are overlaid. The percentage of the population that has a polar or midcell focus is indicated below each panel; 50–100 cells were examined for each sample. C. TnaA-sfGFP focus formation (squares) plotted against amount of indole produced (triangles). The percentage of cells with TnaA-sfGFP foci are plotted from the data in B. Three independent cultures were assayed for indole production, and the mean ± standard deviation is presented.Back to article page