Figure 4. Two conserved sRNAs in the iron stress-response of Synechocystis.

(A) Transcriptional organization and expression of the isiA locus in Synechocystis 6803 and 6714. For annotation details see Figure 2. In both strains, isiA is highly inducible in the -Fe condition (brown graph), while the asRNA IsrR is inversely regulated, suggesting a conserved function. (B) Verification experiment for the presence of IsrR and for the iron stress-dependent upregulation of the isiA mRNA and a separate sRNA from its 5′UTR. The 5S rRNA was used as a loading control. (C) Consensus structure of the IsrR homologs predicted by RNAz⁵⁸.