IraP participates in RpoS recovery after glucose starvation and during stationary phase.

A) Western blots showing RpoS accumulation (no chloramphenicol) after phosphate was added to the MG1655 strain (recovery) or when incubation was continued without phosphate addition. Results are plotted in Fig 1D. B) Western blot against RpoS and the loading control EF-Tu showing RpoS degradation (chase) during (stabilization) and after exit from stationary phase (recovery) in MG1655 and ΔiraP (SB151) strains. Cells were grown in MOPS minimal glucose medium overnight to reach stationary phase. Stationary-phase cells were diluted 5-fold back into fresh medium and chloramphenicol was added after 2 minutes. Samples were taken and treated as described for Fig 1. The graph on the right corresponds to quantification of RpoS degradation (n > 3). C) Western blot against RpoS and the loading control EF-Tu showing RpoS degradation (chase) during and after glucose starvation in MG1655 and ΔiraP (SB151) strains. Samples were taken and treated as described for Fig 1. The graphs on the right and at the bottom correspond to quantification of RpoS degradation (n > 3). D. Stationary Phase, RpoS chase in ira mutants. Western blot of RpoS and the loading control EF-Tu showing RpoS degradation after Chloramphenicol addition (chase) during (Stab, for stabilization) and after exit from stationary phase (Rec for recovery) as in B, but in the following isogenic derivatives of MG1655, carrying different combinations of ira mutant alleles. Strains used: ΔiraP (SB151); ΔiraD (SB364); ΔiraM (SB539); ΔiraP ΔiraD (SB365); ΔiraP ΔiraM (SB540); ΔiraD ΔiraP (SB541); ΔiraD ΔiraM ΔiraP (SB542). Quantitation of triplicates is shown in Fig 2D (stabilization) and 2E (recovery).

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