Cyanobacterial RNA thermometer

The first cyanobacterial RNA thermometer (RNAT) Hsp17 was found in the 5'UTR of "Synechocystis" heat shock "hsp17" mRNA. Further study demonstrated that cyanobacteria commonly use RNATs to control the translation of their heat shock genes. HspA is a homolog of Hsp17 in thermophilic "Thermosynechococcus elongatus". Two more thermometers were found in the 5'UTRs of mesophilic cyanobacteria "A. variabilis" and "Nostoc" "sp". The first RNAT called avashort was shown to regulate translation by masking the AUG translation start site. The second RNAT called avalong, as it has an extended initial hairpin, might involve tertiary interactions and has similarities to the ROSE element.