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. Author manuscript; available in PMC: 2013 Oct 26.
Published in final edited form as: Mol Cell. 2012 Sep 13;48(2):231–241. doi: 10.1016/j.molcel.2012.08.009

Figure 6. High Levels of GTP Kill (p)ppGpp0 Cells Independent of Starvation.

Figure 6

(A) Decreasing GTP levels by decoyinine (50 µg/ml) enhances colony formation of (p)ppGpp0 and ΔcodY (p)ppGpp0 cells on minimal medium.

(B) Increasing GTP levels by guanosine (0.1 mM Guo) decreases colony formation of (p)ppGpp0 suppressors on minimal medium. WT, (p)ppGpp0, (p)ppGpp0 ΔcodY, guaB-65T>C (guaB), and gmk419C>T (gmk) mutants were plated on medium with or without 0.1 mM Guo.

(C) (p)ppGpp0 cells do not survive Guo addition. WT and (p)ppGpp0 cells were grown in liquid medium with casamino acids, treated with 1 mM Guo, and then plated on LB plates at the indicated times after treatment.

(D) Exponential phase cultures 30 minutes after treatment with 1 mM Guo are stained with the fluorescent dyes SYTO9 (green) and propidium iodide (red) to label live and dead cells, respectively.

(E) A mutation in gmk, but not codY or guaB, enables (p)ppGpp0 cells to form colonies in the presence of Guo. WT, (p)ppGpp0, (p)ppGpp0 ΔcodY, (p)ppGpp0 guaB-65T>C (guaB), and (p)ppGpp0 gmk419C>T (gmk) mutants were plated on medium supplemented with 20 amino acids, with or without 0.1 mM Guo.

(F) A mutation in gmk, but not codY and guaB, prevents high levels of GTP in (p)ppGpp0 cells. GTP levels for untreated or Guo-treated (1 mM, 20 minutes) samples were determined by TLC for the same strains as 6E.