Fig. 3: ytfK is required for normal accumulation of (p)ppGpp during phosphate and fatty acid starvation.

Exponentially growing cells of MG1655 (WT) and isogenic deletion strains, ΔrelA, ΔytfK, and ΔrelA ytfK were challenged for different starvations. Samples were taken at the indicated time, after being washed and resuspended in low-phosphate medium to induce phosphate starvation (a), after addition of 250 µg/mL cerulenin to induce fatty acid starvation (b), and after addition of 500 µg/mL L-Valine to induce amino acid starvation (c) (see the Methods section). Nucleotides were extracted and separated by TLC. Representative autoradiograph of the TLC is shown on the left, and quantification is presented on the right panel. Error bars indicate the standard deviations of averages of four independent experiments for phosphate starvation, six independent experiments for fatty acid starvation, and three independent experiments for amino acid starvation. Source data are provided as a Source Data file.