Induction of RSs0680a, RSs2461, and RSs1543 under 1O2 and heat stress depends on both RpoHI and RpoHII. (A) The genetic localization of RSs0680a, RSs2461, and RSs1543 is depicted. RSs0680a and RSs2461 are transcribed together with the upstream gene from an RpoHI/RpoHII promoter. RSs0680a is followed by three homologous sRNAs (RSs0680b to -d). RSs2461 is further processed after cotranscription (4), and the respective processing site is indicated by a dotted line. In contrast, RSs1543 is directly preceded by an RpoHI/RpoHII promoter. A terminating structure is indicated by a stem-loop with a “T” in the loop. (B) Northern blot analysis of RSs0680a, RSs2461, and RSs1543. All three sRNAs are induced after 10 min of 1O2 exposure in the wild-type (WT) and the rpoHI and rpoHII single-deletion strains. This induction is not observed in the rpoHI rpoHII deletion strain. After 10 min of heat stress, all three sRNAs are upregulated. In the case of RSs2461, only the 75-nt fragment is shown, which originates from a 116-nt precursor (4).