arfA antisense RNA regulates MscL excretory activity
Bacteria adapt to acute changes in their environment by processing multiple input stimuli through signal integration and crosstalk to allow fine tuning of gene expression in response to stress. The response to hypoosmotic shock and ribosome stalling occurs through the action of mechanosensitive channels and ribosome rescue mechanisms respectively. However, it is not known if a mechanistic link exists between these stress response pathways. Here we report that the corresponding Large-conductance mechanosensitive channel (mscL) and Alternative ribosome-rescue factor A (arfA) genes are commonly co-located on the genomes of Gammaproteobacteria and display overlap in their respective 3 UTR and 3 CDS. We show this unusual genomic arrangement permits an antisense RNA mediated regulatory control between mscL and arfA and this modulates MscL excretory activity in E. coli. These findings highlight a mechanistic link between osmotic and translational stress responses in E. coli, and further elucidates the previously unknown regulatory function of arfA sRNA.