Introduction

Temperature sensing RNA sequences, known as RNA thermometers, regulate translation by preventing the ribosome from binding the transcript until higher temperatures shift it to an open structure. Several naturally occurring RNA thermometers have been described and synthetic sequences that emulate them have been designed and proved to regulate genetic expression at different temperature ranges. Here, we intend to build a genetic circuit that incorporates two synthetic RNA thermometers, resulting in three discrete states whose transition can be regulated by temperature changes in the medium only. Most notably, our circuit integrates transcriptional and post-transcriptional regulation, widening the spectrum of potential genetic circuit topologies for synthetic biology, with applications that range from basic research to the replacement of chemical inducers for industrial-scale processes.