FIGURE 6.

3′ terminal nucleotide analysis of the rpsO mRNA. All strains carry the rne-1 allele and were exposed to thermal inactivation following immediate addition of rifampicin. Sample time points were withdrawn at times indicated after the blockage of transcription. Ten micrograms of RNA extracted from rne-1 rnr; rne-1 Δrnb; rne-1 Δrnb rnr, and rne-1 Δrnb rnr ΔpcnB were treated with RNase H and the chimeric DNA/RNA oligonucleotide CrpsO as described in Material and Methods. RNAs fragments whose terminal nucleotide matches the transcriptional terminal C residue are identified. Increasing bands correspond to elongated RNAs that vary one nucleotide in size from the neighborhood bands, corresponding to a post-transcriptional added adenosine (A) residue. Cells that carry the pcnB deletion do not present this elongated rpsO mRNA species. A specific 3′ rpsO riboprobe was used to detect these transcripts.