1P-345 : Systematic engineering of L-tryptophan aptamer to construct ligand-responsive RNA-based sensor

The Potential of the riboswitch which implements cis-regulatory mechanism has been highlighted for monitoring various molecules in vivo. Several parameters of riboswitch should be considered to apply it in user-defined condition. However, it is not straightforward to tune the parameters since detailed numeric information between the concentration of the ligand and the strength of expression is required. Here, we demonstrate three strategies to optimize an artificial L-tryptophan riboswitch. We modulated the strength of the promoter or the copy number of the plasmid to optimize dynamic range and fold activation. Then tetA was utilized to amplify the response by tetracycline supplementation. Finally, a riboswitch variants were constructed using an aptamer with distinct affinity to L-tryptophan to adjust the operational range. All strategies could be easily applied to the optimization of other riboswitches owing to their simplicity.