FIG. 5.

RNase protection assay of DsrA stability in an hfq-1 strain. Cells were grown at 30°C in LB broth to an OD₆₀₀ of 0.5 and treated with rifampin to block new transcription. Samples were taken at the indicated times, and RNA was extracted. DsrA was detected using a RNase protection assay and DsrA-specific probe. The minus sign in panel B indicates that the RNA was isolated from a dsrA deletion mutant. (A) DsrA expressed from the chromosome and the plasmid pDDS164. (B) DsrA expressed only from the chromosome. The positions of full-length, processed, read-through, and unstable DsrA transcripts are indicated. Processed DsrA transcripts were also seen when DsrA was expressed from the plasmid but are not shown. Note that in lane 1, no DsrA is detected in RNA isolated from a DsrA deletion strain.