Gene regulation by RNA switches

RNA regions that are involved in gene expression switching are shown in the same color. a) Translation activation of virulence genes in the pathogen Listeria monocytogenes. An increase in temperature melts the secondary structure around the ribosome binding site (RBS) and start codon, allowing ribosome binding and translation initiation. b) Upregulation of an Escherichia coli gene by the DsrA antisense short RNA (sRNA). DsrA RNA pairs with the translational operator of the rpoS gene using two sequences (colored blue and light blue) located within helices 1 and 2. This base pairing exposes translation initiation signals for ribosome binding and increases mRNA stability.