Translational control of bacterial heat shock and virulence genes by temperature-sensing mRNAs

Riboswitches and RNA thermometers are built-in sensory elements that control the fate of mRNAs in response to environmental conditions. Both are comprised of complex RNA structures that undergo a conformational change when a certain chemical or physical signal is present. In bacteria, these elements are usually located in the 5'-untranslated region (5'-UTR). Typical RNA thermometers control translation initiation of heat shock or virulence genes by forming a secondary structure that traps the ribosome binding site (RBS). An increase in temperature to 37 degrees C (virulence genes) or higher (heat shock genes) destabilizes the structure, liberates the RBS and permits formation of the translation initiation complex. Recent findings suggest that RNA thermometers are more widely used than initially anticipated. The molecular details of selected thermometers and the potential advantage of using such riboregulators will be discussed.