FIG. 2.

Analysis of intracellular (p)ppGpp in M. tuberculosis by 2D-TLC. (A) Control nucleotides extracted from ³²P_i-labeled M. tuberculosis H37Rv aerobically grown in normal 7H9 medium during the log phase. (B) Nucleotides extracted from stationary-phase culture of H37Rv (2-week-old culture). These cultures label significantly less well than logarithmically growing cultures, and, thus, this panel has been exposed more heavily. (C) Nucleotides extracted from H37Rv cells labeled and then placed under starvation conditions (resuspension in TBST). (D) Sample prepared as in panel C, but with the SJA16 Δrel strain of H37Rv. (E) Schematic representation of nonradioactive standards run in the same 2D-TLC system. Complementation of the Δrel_Mtb strain with the rel_Mtb gene restored the ability to produce (p)ppGpp under these conditions.