Part:BBa_K4345001

RNA Thermometer Hsp17

Hsp17 is in nature implemented in the mRNA structure of a cyanobacterial (Synechocystis sp.) heatshock gene which is important for stress tolerance. The thermometer is a structural element that is located within the 5’ UTR of protein-coding mRNA. It operates as a reversible molecular zipper that controls the availability of the RBS in its structure. When the temperature increases, the thermometer unzips and the RBS can be detected by the ribosome thus allowing translation of downstream mRNA. When the temperature is below a certain range, the RBS gets trapped.

The 5’ UTR end consists of a single hairpin with an internal asymmetric loop, as seen in the figure below. The secondary structure was predicted by RNAFold. The trapped RBS sequence is highlighted in blue. The start codon is highlighted in green and is located 45 nucleotides downstream from the transcriptional start site which means that the thermometer is very short compared to others that are described.