Monitoring the expression level of coding and non-coding RNAs using a TetR inducing aptamer tag

RNA aptamers have been widely used as regulators for conditional gene expression. The TetR binding aptamer can activate tetracycline repressor TetR controlled gene expression with high efficiency. Here we demonstrate that the aptamer can also activate TetR controlled gene expression when expressed in the context of a natural transcripts. The aptamer was inserted into the untranslated regions of mRNAs as well as into small non-coding RNAs and was expressed both from a plasmid and from an endogenous locus. Our data suggest that the aptamer is a valuable tool to easily monitor the expression level of different RNAs, and it therefore represents a powerful tool for the construction of complex synthetic gene networks.