Figure 10.

Promising novel DBPs suggest FnrS and PsrD play wider roles in stress response networks. (A) A CpxR motif was identified within a strong PO peak near the promoter of FnrS. CpxR is activated in response to inner membrane disruption, such as conditions of alkaline pH and high osmolarity. (B) RNA expression data (Gao et al., 2018) illustrate FnrS induction in alkaline conditions, supporting CpxR as a potential regulator of FnrS. (C) PsrD, an sRNA with no documented function, contains both FNR and Fur motifs within the annotated coding region near an embedded secondary promoter (FNR: +5 to +26 of accepted PsrD TSS, -55 to -34 of alternate TSS; Fur: +32 to +49 accepted TSS, -28 to –11 of alternate TSS). (D) RNA-seq counts (Seo et al., 2014) [GSE72113] highlight PsrD transcription induction under iron-rich and aerobic conditions (as compared to iron-poor and anaerobic conditions, respectively) and additionally showcase the activity of the secondary promoter (purple dashed line) that is ideally positioned to be regulated by the proposed FNR and Fur binding sites. Full-length transcripts have previously been detected at late stationary growth phases (Argaman et al., 2001).