FIGURE 4.

Northern blot analysis of sodB, ptsG, and ompX mRNA fate in pnp mutants. From the same cultures used in Figure 3, samples were removed for RNA isolation from each culture prior to and 2, 5, 10, and 15 min after dipyridyl (A), α-MG (B), or IPTG (C) was added to the culture. An equal amount of RNA from each sample was fractionated on a polyacrylamide or agarose gel, transferred to a nylon membrane, and a Northern blot developed using the 5′-biotinylated RyhB and sodB probe (A), SgrS and ptsG probe (B), or CyaR and ompX probe (C) as described in Materials and Methods. The membranes used for the RyhB, SgrS, or CyaR Northern blots were subsequently stripped by boiling in 0.5% SDS and developed using the ssrA probe as a loading control. The results are representative of two experiments.