Figure 6.

IF3 releases RbfA from 30S ribosomes during stationary phase. (A) Pelleting assay showing that RbfA release by 200 nM RsgA, 50 μM GTP is inhibited by 1.5 mM ppGpp (lane 10). 5 μM IF3 can release RbfA from 30S subunits under this condition (lanes 11 and 12). (B) Quantification of experiments performed in (A). Mean and s.d., n = 2. (C) Growth of WT E. coli (BW25113) in liquid LB medium. (D) Primer extension on total RNA from cells in (C) at 3 h and 10 h detects unprocessed 17S pre-rRNA as a proxy of ribosome biogenesis. (E) Ribosome biogenesis during log phase (3 h, left panel) and stationary phase (10 h, right panel) from tritium labeled cells. Cells were harvested for polysome analysis at 1 min (gray) and 10 min (blue) after the addition of ³H-uridine and 1 min after treatment with chloramphenicol (Cm). Insets: ³H-uridine in polysomes.