Gene expression can be regulated by various mechanisms, including structural transitions in mRNAs in response to temperature change. One such mechanism involves RNA thermometers, elements in the 5′-untranslated region of some bacterial mRNAs. Many RNA thermometers adopt a stem-loop structure including the Shine-Dalgarno (SD) sequence, the binding site of ribosomes. Due to the weak interactions between the base pairs in the stem, the structure readily unfolds with increased temperature. As a result, the SD sequence becomes accessible for ribosomes to initiate translation, allowing for the regulation of protein synthesis. The htrA gene of Salmonella enterica encodes a heat-shock protease. This gene contains an RNA thermometer that belongs to the fourU family. Here, we examine the biological behavior of the htrA RNA thermometer using a bgaB reporter assay. We present results comparing the wild-type thermometer with a mutant containing a more stable stem. Under heat-shock conditions, the wild-type element directed a greater increase in reporter activity, confirming a previous report that the structure of this fourU RNA thermometer influences its biological function. We continue to study other mutants that probe stem stability, with the goal of a more comprehensive understanding of this regulatory element.

Monitoring htrA RNA thermometer activity using a β-galactosidase assay in Escherichia coli

253rd National Meeting (2017)

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