RNA thermometers.

Temperature is an important parameter that free-living cells monitor constantly. The expression of heat-shock, cold-shock and some virulence genes is coordinated in response to temperature changes. Apart from protein-mediated transcriptional control mechanisms, translational control by RNA thermometers is a widely used regulatory strategy. RNA thermometers are complex RNA structures that change their conformation in response to temperature. Most, but not all, RNA thermometers are located in the 5'-untranslated region and mask ribosome-binding sites by base pairing at low temperatures. Melting of the structure at increasing temperature permits ribosome access and translation initiation. Different cis-acting RNA thermometers and a trans-acting thermometer will be presented.