Structure and function of RNA thermometers

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RNA thermometers control translation initiation of many bacterial heat shock and virulence genes in response to elevated temperatures. They are located in the 5’-untranslated region (5’-UTR), which folds into a complex structure that blocks access to the Shine-Dalgarno (SD) sequence at low temperatures. A temperature upshift to 37 °C (virulence genes) or higher (heat shock genes) induces melting of that structure making the SD sequence available to the 30S ribosome. We are studying individual members of three different classes of RNA thermometers, socalled ROSE (Repression Of heat Shock gene Expression), fourU (four uridines) and Cyotherm (cyanobacterial thermometer) elements. The major aim of future studies is to demonstrate the physiological importance of these RNA thermometers in the bacterial stress and virulence response. Other goals are to define a minimal ROSE element and to closely examine fourU thermometers from pathogenic microorganisms. In addition, we plan to investigate potential RNA thermometers from thermophilic bacteria. RNA thermometers that act by mechanisms other than melting have been predicted upstream of cold shock genes and a virulence gene from Staphylococcus aureus. The structure and function of these candidates will be studied.