Figure 7. The accessibility of the riboswitch response curve depends on application category and associated system restrictions.
Categories include an inducible regulatory system with (A) no ligand limitations or (B) a ligand concentration upper limit, and (C) an autonomous regulatory system with defined lower and upper limits for the ligand concentration. The accessible dynamic range (η) for each response curve depends on the system restrictions. The properties of other components in the network will dictate which riboswitch design best meets performance requirements. For example, under the autonomous regulatory system (C) the red curve may be more appropriate for the regulation of cytotoxic genes, the orange curve may be more appropriate for the regulation of enzymes with low catalytic activity, and the blue curve may be more appropriate for regulatory networks that require a large change in protein levels.